Section 731 japan

Section 731 japan DEFAULT

Unit 731

Part of IJN army, infamous for war crimes

Unit 731
Unit 731 - Complex.jpg

The Unit 731 complex. Two prisons are hidden in the center of the main building.

LocationPingfang, Harbin, Heilungkiang, Manchukuo
Coordinates45°36′30″N126°37′55″E / 45.60833°N 126.63194°E / 45.60833; 126.63194Coordinates: 45°36′30″N126°37′55″E / 45.60833°N 126.63194°E / 45.60833; 126.63194

Attack type

Human experimentation
Biological warfare
Chemical warfare
WeaponsBiological weapons
Chemical weapons
DeathsEstimated 200,000[1] or 300,000[2]–400,000 or higher from biological warfare
Over 3,000 from inside experiments (not including branches, 1940–1945 only)[3]: 20 
At least 10,000 prisoners died[4]
PerpetratorsSurgeon GeneralShirō Ishii
Lt. GeneralMasaji Kitano
Epidemic Prevention and Water Purification Department

Unit 731 (Japanese: 731部隊, Hepburn: Nana-san-ichi Butai),[note 1] short for Manshu Detachment 731 and also known as the Kamo Detachment,[3]: 198  and Ishii Unit,[5] was a covert biological and chemical warfareresearch and development unit of the Imperial Japanese Army that engaged in lethal human experimentation during the Second Sino-Japanese War (1937–1945) and World War II. It was responsible for some of the most notorious war crimes which were committed by the armed forces of Imperial Japan. Unit 731 was based in the Pingfang district of Harbin, the largest city in the Japanese puppet state of Manchukuo (now Northeast China), and had active branch offices throughout China and Southeast Asia.

It was officially known as the Epidemic Prevention and Water Purification Department of the Kwantung Army (関東軍防疫給水部本部, Kantōgun Bōeki Kyūsuibu Honbu). Originally set up by the Kenpeitaimilitary police of the Empire of Japan, Unit 731 was taken over and commanded until the end of the war by General Shirō Ishii, a combat medic officer in the Kwantung Army. The facility itself was built in 1935 as a replacement for the Zhongma Fortress, and Ishii and his team used it to expand their capabilities. The program received generous support from the Japanese government until the end of the war in 1945. Unit 731 and the other units of the Epidemic Prevention and Water Purification Department operated biological weapon production, testing, deployment and storage facilities. They routinely conducted tests on human beings (who were internally referred to as "logs"). Additionally, the biological weapons were tested in the field on cities and towns in China. Estimates of those who were killed by Unit 731 and its related programs range up to half a million people.

The researchers in Unit 731 were secretly given immunity by the United States in exchange for the data which they gathered during their human experimentation.[6] Other researchers that the Soviet forces managed to arrest first were tried at the Khabarovsk War Crime Trials in 1949. The Americans did not try the researchers so that the information and experience gained in bio-weapons could be co-opted into their biological warfare program, much as they had done with German researchers in Operation Paperclip.[7] Victim accounts were then largely ignored or dismissed in the west as communist propaganda.[8]


Building on the site of the Harbin bioweapon facility of Unit 731

In 1932, Surgeon GeneralShirō Ishii (石井四郎, Ishii Shirō), chief medical officer of the Imperial Japanese Army and protégé of Army MinisterSadao Araki was placed in command of the Army Epidemic Prevention Research Laboratory (AEPRL). Ishii organized a secret research group, the "Tōgō Unit", for chemical and biological experimentation in Manchuria. Ishii had proposed the creation of a Japanese biological and chemical research unit in 1930, after a two-year study trip abroad, on the grounds that Western powers were developing their own programs.

One of Ishii's main supporters inside the army was Colonel Chikahiko Koizumi, who later became Japan's Health Minister from 1941 to 1945. Koizumi had joined a secret poison gas research committee in 1915, during World War I, when he and other Imperial Japanese Army officers were impressed by the successful German use of chlorine gas at the Second Battle of Ypres, in which the Allies suffered 5,000 deaths and 15,000 wounded as a result of the chemical attack.[9][10]

Zhongma Fortress[edit]

Unit Tōgō was implemented in the Zhongma Fortress, a prison/experimentation camp in Beiyinhe, a village 100 km (62 mi) south of Harbin on the South Manchuria Railway. Prisoners were generally well fed on the usual diet of rice or wheat, meat, fish, and occasionally even alcohol, with the intent of having prisoners in their normal state of health at the beginning of experiments. Over several days, prisoners were eventually drained of blood and deprived of nutrients and water. Their deteriorating health was recorded. Some were also vivisected. Others were deliberately infected with plague bacteria and other microbes.[11]

In the autumn of 1934, a prison break, which jeopardized the facility's secrecy along with a later explosion (believed to be sabotage) in 1935 led Ishii to shut down Zhongma Fortress. He then received authorization to move to Pingfang, approximately 24 km (15 mi) south of Harbin, to set up a new, much larger facility.[12]

Unit 731[edit]

In 1936, Emperor Hirohito authorized by decree the expansion of this unit and its integration into the Kwantung Army as the Epidemic Prevention Department.[13] It was divided at that time into the "Ishii Unit" and "Wakamatsu Unit" with a base in Hsinking. From August 1940, the units were known collectively as the "Epidemic Prevention and Water Purification Department of the Kwantung Army (関東軍防疫給水部本部)"[14] or "Unit 731" (満州第731部隊) for short.

A close up photo of the Unit 731 square building taken by the aviation and photography class of Unit 731 in 1940

Other units[edit]

Main article: Epidemic Prevention and Water Purification Department

In addition to the establishment of Unit 731, the decree also called for the establishment of an additional biological warfare development unit called the Kwantung Army Military Horse Epidemic Prevention Workshop (later referred to as Manchuria Unit 100) and a chemical warfare development unit called the Kwantung Army Technical Testing Department (later referred to as Manchuria Unit 516). After the Japanese invasion of China in 1937, sister chemical and biological warfare units were founded in major Chinese cities, and were referred to as Epidemic Prevention and Water Supply Units. Detachments included Unit 1855 in Beijing, Unit Ei 1644 in Nanjing, Unit 8604 in Guangzhou and later, Unit 9420 in Singapore. All of these units comprised Ishii's network, and at its height in 1939, was composed of more than 10,000 personnel.[15] Medical doctors and professors from Japan were attracted to join Unit 731 by the rare opportunity to conduct human experimentation and strong financial support from the Army.[16]


A special project code-named Maruta used human beings for experiments. Test subjects were gathered from the surrounding population and were sometimes euphemistically referred to as "logs" (丸太, maruta), used in such contexts as "How many logs fell?". This term originated as a joke on the part of the staff because the official cover story for the facility given to the local authorities was that it was a lumber mill. However, in an account by a man who worked as a junior uniformed civilian employee of the Imperial Japanese Army in Unit 731, the project was internally called "Holzklotz", which is a German word for log.[17] In a further parallel, the corpses of "sacrificed" subjects were disposed of by incineration.[18] Researchers in Unit 731 also published some of their results in peer-reviewed journals, writing as though the research had been conducted on non-human primates called "Manchurian monkeys" or "long-tailed monkeys".[19]

The test subjects were selected to give a wide cross-section of the population and included common criminals, captured bandits, anti-Japanese partisans, political prisoners, the homeless and mentally handicapped, and also people rounded up by the Kempeitai military police for alleged "suspicious activities". They included infants, men, the elderly, and pregnant women. The members of the unit included approximately 300 researchers, including doctors and bacteriologists.[20] Many had been desensitized to performing cruel experiments from experience in animal research.[21]

Nakagawa Yonezo, professor emeritus at Osaka University, studied at Kyoto University during the war, and, while he was there, watched footage of human experiments and executions from Unit 731. He testified about the playfulness of the experimenters:[22]

"Some of the experiments had nothing to do with advancing the capability of germ warfare, or of medicine. There is such a thing as professional curiosity: ‘What would happen if we did such and such?’ What medical purpose was served by performing and studying beheadings? None at all. That was just playing around. Professional people, too, like to play."

Prisoners were injected with diseases, disguised as vaccinations,[23] to study their effects. To study the effects of untreated venereal diseases, male and female prisoners were deliberately infected with syphilis and gonorrhea, then studied. Prisoners were also repeatedly subject to rape by guards.[24]


Thousands of men, women, children and infants interned at prisoner of war camps were subjected to vivisection, often without anesthesia and usually ending with the death of the victim.[25][26] In a video interview, former Unit member Okawa Fukumatsu admitted to having vivisected a pregnant woman.[27] Vivisections were performed on prisoners after infecting them with various diseases. Researchers performed invasive surgery on prisoners, removing organs to study the effects of disease on the human body.[28]

Human Dissection Experiment Room

Prisoners had limbs amputated in order to study blood loss. Those limbs that were removed were sometimes re-attached to the opposite sides of the body. Some prisoners had their stomachs surgically removed and the esophagus reattached to the intestines. Parts of organs, such as the brain, lungs, and liver, were removed from some prisoners.[26] Imperial Japanese Army surgeon Ken Yuasa suggests that the practice of vivisection on human subjects was widespread even outside Unit 731,[29] estimating that at least 1,000 Japanese personnel were involved in the practice in mainland China.[30]

Biological warfare[edit]

The ruins of a boiler building on the site of the bioweapon facility of Unit 731

Unit 731 and its affiliated units (Unit 1644 and Unit 100 among others) were involved in research, development and experimental deployment of epidemic-creating biowarfare weapons in assaults against the Chinese populace (both military and civilian) throughout World War II. Plague-infected fleas, bred in the laboratories of Unit 731 and Unit 1644, were spread by low-flying airplanes upon Chinese cities, including coastal Ningbo and Changde, Hunan Province, in 1940 and 1941.[5] This military aerial spraying killed tens of thousands of people with bubonic plague epidemics. An expedition to Nanking involved spreading typhoid and paratyphoid germs into the wells, marshes, and houses of the city, as well as infusing them into snacks to be distributed among the locals. Epidemics broke out shortly after, to the elation of many researchers, where it was concluded that paratyphoid fever was "the most effective" of the pathogens.[31][32]: xii, 173 

At least 12 large-scale field trials of biological weapons were performed, and at least 11 Chinese cities were attacked with biological agents. An attack on Changda in 1941 reportedly led to approximately 10,000 biological casualties and 1,700 deaths among ill-prepared Japanese troops, with most cases due to cholera.[4] Japanese researchers performed tests on prisoners with bubonic plague, cholera, smallpox, botulism, and other diseases.[33] This research led to the development of the defoliation bacilli bomb and the flea bomb used to spread bubonic plague.[34] Some of these bombs were designed with porcelain shells, an idea proposed by Ishii in 1938.

These bombs enabled Japanese soldiers to launch biological attacks, infecting agriculture, reservoirs, wells, as well as other areas with anthrax, plague-carrier fleas, typhoid, dysentery, cholera or other deadly pathogens. During biological bomb experiments, researchers dressed in protective suits would examine the dying victims. Infected food supplies and clothing were dropped by airplane into areas of China not occupied by Japanese forces. In addition, poisoned food and candies were given to unsuspecting victims.

During the final months of World War II, Japan planned to use plague as a biological weapon against San Diego, California. The plan was scheduled to launch on September 22, 1945, but Japan surrendered five weeks earlier.[35][36][37][38]Plague fleas, infected clothing and infected supplies encased in bombs were dropped on various targets. The resulting cholera, anthrax, and plague were estimated to have killed at least 400,000 Chinese civilians.[39]Tularemia was also tested on Chinese civilians.[40]

Due to pressure from numerous accounts of the bio-warfare attacks, Chiang Kai-shek sent a delegation of army and foreign medical personnel in November 1941 to document evidence and treat the afflicted. A report on the Japanese use of plague-infested fleas on Changde was made widely available the following year, but was not addressed by the Allied Powers until Franklin D. Roosevelt issued a public warning in 1943 condemning the attacks.[41][42]

Weapon testing[edit]

Human targets were used to test grenades positioned at various distances and in various positions. Flamethrowers were tested on people.[43] Victims were also tied to stakes and used as targets to test pathogen-releasing bombs, chemical weapons, shrapnel bombs with varying amounts of fragments, and explosive bombs as well as bayonets and knives.

To determine the best course of treatment for varying degrees of shrapnel wounds sustained on the field by Japanese Soldiers, Chinese prisoners were exposed to direct bomb blasts. They were strapped, unprotected, to wooden planks that were staked into the ground at increasing distances around a bomb that was then detonated. It was surgery for most, autopsies for the rest.

—Unit 731, Nightmare in Manchuria [44][45]

Other experiments[edit]

In other tests, subjects were deprived of food and water to determine the length of time until death; placed into low-pressure chambers until their eyes popped from the sockets; experimented upon to determine the relationship between temperature, burns, and human survival; hung upside down until death; crushed with heavy objects; electrocuted; dehydrated with hot fans; placed into centrifuges and spun until death; injected with animal blood; exposed to lethal doses of x-rays; subjected to various chemical weapons inside gas chambers; injected with sea water; and burned or buried alive.[46][47] In addition to chemical agents, the properties of many different toxins were also investigated by the Unit. To name a few, prisoners were exposed to tetrodotoxin (pufferfish or fugu venom); heroin; Korean bindweed; bactal; and castor-oil seeds (ricin).[48][49] Massive amounts of blood were drained from some prisoners in order to study the effects of blood loss according to former Unit 731 vivisectionist Okawa Fukumatsu. In one case, at least half a litre of blood was drawn at two to three-day intervals.[50]

Unit 731 also performed transfusion experiments with different blood types. Unit member Naeo Ikeda wrote:

In my experience, when A type blood 100 cc was transfused to an O type subject, whose pulse was 87 per minute and temperature was 35.4 degrees C, 30 minutes later the temperature rose to 38.6 degrees with slight trepidation. Sixty minutes later the pulse was 106 per minute and the temperature was 39.4 degrees. Two hours later the temperature was 37.7 degrees, and three hours later the subject recovered. When AB type blood 120 cc was transfused to an O type subject, an hour later the subject described malaise and psychroesthesia in both legs. When AB type blood 100 cc was transfused to a B type subject, there seemed to be no side effect.

— Man, Medicine, and the State: The Human Body as an Object of Government Sponsored Medical Research in the 20th Century (2006) p. 38-39

Unit 731 tested many different chemical agents on prisoners, and had a building dedicated to gas experiments. Some of the agents tested were: mustard gas; lewisite; cyanic acid gas; white phosphorus; adamsite; and phosgene gas.[51] A former army major and technician gave the following testimony anonymously (at the time of the interview, this man was a professor emeritus at a national university):

In 1943, I attended a poison gas test held at the Unit 731 test facilities. A glass-walled chamber about three meters square and two meters high was used. Inside of it, a Chinese man was blindfolded, with his hands tied around a post behind him. The gas was adamsite (sneezing gas), and as the gas filled the chamber the man went into violent coughing convulsions and began to suffer excruciating pain. More than ten doctors and technicians were present. After I had watched for about ten minutes, I could not stand it any more, and left the area. I understand that other types of gasses were also tested there.

— Hal Gold, Japan's Infamous Unit 731, p. 349 (2019)

Unit 100 also experimented with Toxic Gas. Phone booth-like tanks were used as portable gas chambers for the prisoners. Some were forced to wear various types of gas masks, others wore military uniform and some had no clothes on at all.

Some of the tests have been described as "psychopathically sadistic, with no conceivable military application". For example, one experiment documented the time it took for three-day-old babies to freeze to death.[52][53]

Unit 731 also tested chemical weapons on prisoners in field conditions. A report authored by unknown researcher in the Kamo Unit (Unit 731) describes a large human experiment of yperite gas (mustard gas) on September 7—10, 1940. Twenty subjects were divided into three groups and placed in combat emplacements, trenches, gazebos, and observatories. One group was clothed with Chinese underwear, no hat, and no mask, and was subjected to as much as 1,800 field gun rounds of yperite gas over 25 minutes. Another group was clothed in summer military uniform and shoes; three had masks and another three had no mask. They also were exposed to as much as 1,800 rounds of yperite gas. A third group was clothed in summer military uniform, three with masks and two without masks, and were exposed to as much as 4,800 rounds. Then their general symptoms and damage to skin, eye, respiratory organs, and digestive organs were observed at 4 hours, 24 hours, and 2, 3, and 5 days after the shots. Injecting the blister fluid from one subject into another subject and analyses of blood and soil were also performed. Five subjects were forced to drink a solution of yperite and lewisite gas in water, with or without decontamination. The report describes conditions of every subject precisely without mentioning what happened to them in the long run.[54] The following is an excerpt of one of these reports:

Number 376, dugout of the first area:

September 7, 1940, 6 pm: Tired and exhausted. Looks with hollow eyes. Weeping redness of the skin of the upper part of the body. Eyelids edematous, swollen. Epiphora. Hyperemic comjunctivae.

September 8, 1940, 6 am: Neck, breast, upper abdomen and scrotum weeping, reddened, swollen. Covered with millet-seed-size to bean-size blisters. Eyelids and conjunctivae hyperemic and edematous. Had difficulties opening the eyes.

September 8, 6 pm: Tired and exhausted. Feels sick. Body temperature 37 degrees Celsius. Mucous and bloody erosions across the shoulder girdle. Abundant mucous nose secretions. Abdominal pain. Mucous and bloody diarrhea. Proteinuria.

September 9, 1940, 7 am: Tired and exhausted. Weakness of all four extremeties.

Low morale. Body temperature 37 degrees Celsius. Skin of the face still weeping.

— Man, Medicine, and the State: The Human Body as an Object of Government Sponsored Medical Research in the 20th Century (2006) p. 187

Frostbite testing[edit]

Army Engineer Hisato Yoshimura conducted experiments by taking captives outside, dipping various appendages into water of varying temperatures, and allowing the limb to freeze.[55] Once frozen, Yoshimura would strike their affected limbs with a short stick, "emitting a sound resembling that which a board gives when it is struck'".[56] Ice was then chipped away, with the affected area being subjected to various treatments such as being doused in water, exposed to the heat of fire etc.

Members of the Unit referred to Yoshimura as a “scientific devil” and a “cold blooded animal” because he would conduct his work with strictness.[57] Naoji Uezono, a member of Unit 731, described in a 1980s interview a grisly scene where Yoshimura had “two naked men put in an area 40-50 degrees below zero and researchers filmed the whole process until [the subjects] died. [The subjects] suffered such agony they were digging their nails into each other’s flesh”.[58] Yoshimura’s lack of remorse was evident in an article he wrote for the Journal Of Japanese Physiology in 1950 in which he admitted to using 20 children and a 3-day-old infant in experiments which exposed them to zero-degree-celsius ice and salt water.[59] Although this article drew criticism, Yoshimura denied any guilt when contacted by a reporter from the Mainichi Shinbun (a Japanese newspaper).[60][61] Yoshimura developed a “resistance index of frostbite” based on the mean temperature 5 to 30 minutes after immersion in freezing water, the temperature of the first rise after immersion, and the time until the temperature first rises after immersion. In a number of separate experiments it was then determined how these parameters depend on the time of day a victim’s body part was immersed in freezing water, the surrounding temperature and humidity during immersion, how the victim had been treated before the immersion (“after keeping awake for a night”, “after hunger for 24 hours”, “after hunger for 48 hours”, “immediately after heavy meal”, “immediately after hot meal”, “immediately after muscular exercise”, “immediately after cold bath”, “immediately after hot bath”), what type of food the victim had been fed over the five days preceding the immersions with regard to dietary nutrient intake (“high protein (of animal nature)”, “high protein (of vegetable nature)”, “low protein intake”, and “standard diet”) and salt intake (45 g NaCl per day, 15 g NaCl per day, no salt).[62] This original data is seen in the attached figure.

Scan Of Yoshimura Hisato's Frostbite Research Data


Unit members orchestrated forced sex acts between infected and non-infected prisoners to transmit the disease, as the testimony of a prison guard on the subject of devising a method for transmission of syphilis between patients shows:

"Infection of venereal disease by injection was abandoned, and the researchers started forcing the prisoners into sexual acts with each other. Four or five unit members, dressed in white laboratory clothing completely covering the body with only eyes and mouth visible, rest covered, handled the tests. A male and female, one infected with syphilis, would be brought together in a cell and forced into sex with each other. It was made clear that anyone resisting would be shot."[63]

After victims were infected, they were vivisected at different stages of infection, so that internal and external organs could be observed as the disease progressed. Testimony from multiple guards blames the female victims as being hosts of the diseases, even as they were forcibly infected. Genitals of female prisoners that were infected with syphilis were called "jam filled buns" by guards.[64]

Some children grew up inside the walls of Unit 731, infected with syphilis. A Youth Corps member deployed to train at Unit 731 recalled viewing a batch of subjects that would undergo syphilis testing: "one was a Chinese woman holding an infant, one was a White Russian woman with a daughter of four or five years of age, and the last was a White Russian woman with a boy of about six or seven."[64] The children of these women were tested in ways similar to their parents, with specific emphasis on determining how longer infection periods affected the effectiveness of treatments.

Rape and forced pregnancy[edit]

Female prisoners were forced to become pregnant for use in experiments. The hypothetical possibility of vertical transmission (from mother to child) of diseases, particularly syphilis, was the stated reason for the torture. Fetal survival and damage to mother's reproductive organs were objects of interest. Though "a large number of babies were born in captivity", there have been no accounts of any survivors of Unit 731, children included. It is suspected that the children of female prisoners were killed after birth or aborted.[64]

While male prisoners were often used in single studies, so that the results of the experimentation on them would not be clouded by other variables, women were sometimes used in bacteriological or physiological experiments, sex experiments, and as the victims of sex crimes. The testimony of a unit member that served as a guard graphically demonstrated this reality:

"One of the former researchers I located told me that one day he had a human experiment scheduled, but there was still time to kill. So he and another unit member took the keys to the cells and opened one that housed a Chinese woman. One of the unit members raped her; the other member took the keys and opened another cell. There was a Chinese woman in there who had been used in a frostbite experiment. She had several fingers missing and her bones were black, with gangrene set in. He was about to rape her anyway, then he saw that her sex organ was festering, with pus oozing to the surface. He gave up the idea, left and locked the door, then later went on to his experimental work."[64]

Prisoners and victims[edit]

In 2002, Changde, China, site of the plague flea bombing, held an "International Symposium on the Crimes of Bacteriological Warfare" which estimated that the number of people killed by the Imperial Japanese Army germ warfare and other human experiments was around 580,000.[32]: xii, 173  The American historian Sheldon H. Harris states that over 200,000 died.[65][66] In addition to Chinese casualties, 1,700 Japanese troops in Zhejiang during Zhejiang-Jiangxi campaign were killed by their own biological weapons while attempting to unleash the biological agent, indicating serious issues with distribution.[67]

At least 3,000 men, women, and children[3]: 117 [67]—from which at least 600 every year were provided by the Kempeitai[68] were subjected to experimentation conducted by Unit 731 at the camp based in Pingfang alone, which does not include victims from other medical experimentation sites, such as Unit 100.[69] Although 3,000 internal victims is the widely accepted figure in the literature, former Unit member Okawa Fukumatsu refuted it in a video interview. He stated that there were at least over 10,000 victims of internal experiments at the Unit, and that he himself vivisected thousands.[70]

According to A. S. Wells, the majority of victims were Chinese[29] with a lesser percentage being Russian, Mongolian, and Korean. They may also have included a small number of European, American, Indian, Australian and New Zealander prisoners of war.[71][72][73][74] One member of the Japanese Youth Corp, also known as the Yokusan Sonendan, who worked for Unit 731, stated that not only were Chinese, Russians, and Koreans present, but also Americans, British, and Frenchmen.[75] Sheldon H. Harris documented that the victims were generally political dissidents, communist sympathizers, ordinary criminals, impoverished civilians, and the mentally handicapped.[76] Author Seiichi Morimura estimates that almost 70% of the victims who died in the Pingfang camp were Chinese (including both military and civilian),[77] while close to 30% of the victims were Russian.[78]

Imprisoned as a POW at the Mukden camp (housing American, British, Australian and New Zealand soldiers), which was not part of Unit 731, Robert Peaty (1903–1989), a Major in the Royal Army Ordnance Corps, was the senior ranking allied officer. During his captivity, he kept a secret diary.[79][80] He was interviewed by the Imperial War Museum in 1981, and the audio recording tape reels are in the IWM's archives.[81] Peaty recounts: "I was reminded of Dante’s Inferno – abandon hope all ye who enter here ...." His diary recorded the regular injections of infectious diseases that were disguised as preventative vaccinations. His entry for January 30, 1943 notes: "Everyone received a 5 cc Typhoid-paratyphoid A inoculation." The February 23, 1943 entry read: "Funeral service for 142 dead. 186 have died in 5 days, all Americans."[82][83]

A sketch of the prison cells, done by a member of Unit 731. The octagonal sketch represents the pressure chamber.

No one who entered Unit 731 came out alive. Prisoners were usually received into Unit 731 at night in motor vehicles painted black with a ventilation hole but no windows.[84] The vehicle would pull up at the main gates and one of the drivers would go to the guardroom and report to the guard. That guard would then telephone to the "Special Team" in the inner-prison (Shiro Ishii's brother was head of this Special Team).[85][86] Then, the prisoners would be transported through a secret tunnel dug under the facade of the central building to the inner-prisons.[87] One of the prisons housed women and children (Building 8), while the other prison housed men (Building 7). Once at the inner-prison, technicians would take samples of the prisoners' blood and stool, test their kidney function and collect other physical data.[88] Once deemed healthy and fit for experimentation, prisoners lost their names and were given a three digit number which they retained until their death. Whenever prisoners died after the experiments they had been subjected to, a clerk of the 1st Division struck their numbers off an index card and took the deceased prisoner's manacles to be put on new arrivals to the prison.[89]

There is at least one recorded instance of "friendly" social interaction between prisoners and Unit 731 staff. Technician Naokata Ishibashi interacted with two female prisoners. One prisoner was a 21 year old Chinese woman, the other a Soviet girl who was 19 years of age. Ishibashi asked where she came from and learned that she was from Ukraine. The two prisoners told Ishibashi that they had not seen their faces in a mirror since being captured, and begged him to get one. Ishibashi sneaked a mirror to them through a hole in the cell door.[90] Prisoners were repeatedly re-used for experiments as long as they were healthy enough. The average life expectancy of a prisoner once they had entered the Unit was 2 months. Some prisoners were alive in the Unit for over 12 months, and many female prisoners gave birth in the Unit.[91]

The prison cells had wooden floors and a squat toilet in each. There was space between the outer walls of the cells and the outer walls of the prison, enabling the guards to walk behind the cells. Each cell door had a small window in it. Chief of the Personnel Division of the Kwantung Army Headquarters Tamura Tadashi testified that when he was shown the inner-prison, he looked into the cells and saw living people in chains, some moved around, others were lying on the bare floor and were in a very sick and helpless condition.[92][93] Former Unit 731 Youth Corps member Yoshio Shinozuka testified that the windows in these prison doors were so small that it was difficult to see in.[94] The inner-prison was a highly secured building complete with cast-iron doors.[85] No one could enter without special permits and an ID pass with a photograph, and the entry/exit times were recorded.[94] The "special team" worked in these two inner-prison buildings. This team wore white overall suits, army hats, rubber boots, and pistols strapped to their sides.[85]

A former member of the Special Team (who insisted on anonymity) recalled in 1995 his first vivisection conducted at the Unit:

"He didn't struggle when they led him into the room and tied him down. But when I picked up the scalpel, that's when he began screaming. I cut him open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony. He made this unimaginable sound, he was screaming so horribly. But then finally he stopped. This was all in a day's work for the surgeons, but it really left an impression on me because it was my first time."

— Anonymous, New York Times (17 March 1995)

Other sources suggest that it was the usual practice in the Unit for surgeons to stuff a rag (or medical gauze) into the mouth of prisoners before commencing vivisection, in order to stifle any screaming.[95]

Despite the prison's status as a highly secure building, at least one unsuccessful escape attempt did occur. Corporal Kikuchi Norimitsu testified that he was told by another unit member that a prisoner "had shown violence and had struck the experimenter with a door handle" and then "jumped out of the cell and ran down the corridor, seized the keys and opened the iron doors and some of the cells. Some of the prisoners managed to jump out but these were only the bold ones. These bold ones were shot".[96] Seiichi Morimura in his book "The Devil's Feast" went into some greater detail regarding this escape attempt. Two Russian male prisoners were in a cell with handcuffs on, one of them lay flat on the floor pretending to be sick. This got the attention of a staff member who saw it as an unusual condition. That staff member decided to enter the cell. The Russian lying on the floor suddenly sprang up and knocked the guard down. The two Russians opened their handcuffs, took the keys and opened some other cells while yelling. Some prisoners, including Russian and Chinese, were frantically roaming the corridors and kept yelling and shouting. One Russian shouted to the members of Unit 731, demanding to be shot rather than used as an experimental object. This Russian was shot to death.[97] One staff member who was an eyewitness at this escape attempt recalled: "spiritually we were all lost in front of the 'marutas' who had no freedom and no weapons. At that time we understood in our hearts that justice was not on our side".[97] Unfortunately for the prisoners of Unit 731, escape was an impossibility. Even if they had managed to escape the quadrangle (itself a heavily fortified building full of staff), they would have had to get over a 3 meter high brick wall surrounding the complex, and then across a dry moat filled with electrified wire running around the perimeter of the complex (able to be seen in aerial pictures of the Unit).[98]

Interestingly, simply being Japanese was no protection from potentially becoming a victim of the Unit and subjected to vivisection just like the prisoners. Yoshio Tamura, an assistant in the Special Team, recalled that Yoshio Sudō, an employee of the first division at Unit 731, became infected with bubonic plague as a result of the production of plague bacteria. The Special Team was then ordered to vivisect Sudō. Tamura recalled:

"Sudō had, a few days previously, been interested in talking about women, but now he was thin as a rake, with many purple spots over his body. A large area of scratches on his chest were bleeding. He painfully cried and breathed with difficulty. I sanitised his whole body with disinfectant. Whenever he moved, a rope around his neck tightened. After Sudō's body was carefully checked [by the surgeon], I handed a scalpel to [the surgeon] who, reversely gripping the scalpel, touched Sudō's stomach skin and sliced downward. Sudō shouted "brute!" and died with this last word."

— Criminal History Of Unit 731 Of The Japanese Military, pp. 118–119 (1991)

Additionally, Unit 731 Youth Corps member Yoshio Shinozuka testified that his friend junior assistant Mitsuo Hirakawa was vivisected as a result of being accidentally infected with plague.[99]

Known unit members[edit]

In April 2018, the National Archives of Japan disclosed a nearly complete list of 3,607 members of Unit 731 to Katsuo Nishiyama, a professor at Shiga University of Medical Science. Nishiyama reportedly intends to publish the list online to encourage further study into the unit.[100]

Previously disclosed members include:

  • Lieutenant General Shirō Ishii
  • Lieutenant Colonel Ryoichi Naito, founder of the pharmaceutical company Green Cross
  • Professor, Major General Masaji Kitano, commander, 1942–1945[4][101]: 137 
  • Yoshio Shinozuka
  • Yasuji Kaneko
  • Kazuhisa Kanazawa, chief of the 1st Division of Branch 673 of Unit 731
  • Ryoichiro Hotta, member of the Hailar Branch of Unit 731
  • Shigeo Ozeki, civilian employee[3]: 243 
  • Kioyashi Mineoi, civilian employee[3]: 243 
  • Masateru Saito, civilian employee[3]: 243 
  • Major General Hitoshi Kikuchi, head of Research Division, 1942–1945[101]: 133 
  • Lieutenant General [unknown first name] Yasazaka, doctor[101]: 241 
  • Yoshio Furuichi, student at Sunyu Branch of Unit 731[3]: 243 

There were also twelve members who were formally tried and sentenced in the Khabarovsk War Crime Trials.

Other suspected Japanese war criminals who were never indicted include three postwar prime ministers: Hatoyama Ichirō (1954–1956), Ikeda Hayato (1960–1964), and Kishi Nobusuke (1957).[102]

NameMilitary positionUnit position[3]: 5 UnitSentenced years in labor camp[3]: 534–535 
Kiyoshi Shimizu Lieutenant colonelChief of General Division, 1939–1941, Head of Production Division, 1941–1945[101]: 131 73125
Otozō YamadaGeneralDirect controller, 1944–1945[101]: 232 731, 10025
Ryuji Kajitsuka Lieutenant general of the Medical ServiceChief of the Medical Administration[101]: 131 73125
Takaatsu Takahashi Lieutenant general of the Veterinary ServiceChief of the Veterinary Service73125
Tomio Karasawa Major of the Medical ServiceChief of a section73120
Toshihide Nishi Lieutenant colonel of the Medical ServiceChief of a division73118
Masao Onoue Major of the Medical ServiceChief of a branch73112
Zensaku Hirazakura LieutenantOfficer10010
Kazuo Mitomo Senior sergeantMember73115
Norimitsu Kikuchi CorporalProbationer medical orderlyBranch 6432
Yuji Kurushima [none]Laboratory orderlyBranch 1623
Shunji SatoMajor general of the Medical ServiceChief of the Medical Service[101]: 192 731, 164420


Unit 731 was divided into eight divisions:

  • Division 1: research on bubonic plague, cholera, anthrax, typhoid and tuberculosis using live human subjects; for this purpose, a prison was constructed to contain around three to four hundred people
  • Division 2: research for biological weapons used in the field, in particular the production of devices to spread germs and parasites
  • Division 3: production of shells containing biological agents; stationed in Harbin
  • Division 4: bacteria mass-production and storage[103]
  • Division 5: training of personnel
  • Divisions 6–8: equipment, medical and administrative units


Main article: Epidemic Prevention and Water Purification Department

The Harbin bioweapon facility is open to visitors
Information sign at the site today

Unit 731 had other units underneath it in the chain of command; there were several other units under the auspice of Japan's biological weapons programs. Most or all Units had branch offices, which were also often referred to as "Units". The term Unit 731 can refer to the Harbin complex itself, or it can refer to the organization and its branches, sub-Units and their branches.

The Unit 731 complex covered six square kilometres (2.3 square miles) and consisted of more than 150 buildings. The design of the facilities made them hard to destroy by bombing. The complex contained various factories. It had around 4,500 containers to be used to raise fleas, six cauldrons to produce various chemicals, and around 1,800 containers to produce biological agents. Approximately 30 kilograms (66 pounds) of bubonic plague bacteria could be produced in a few days.

Some of Unit 731's satellite (branch) facilities are still in use by various Chinese industrial companies. A portion has been preserved and is open to visitors as a War Crimes Museum.[104]


Unit 731 had branches in Linkou (Branch 162), Mudanjiang, Hailin (Branch 643), Sunwu (Branch 673), Toan and Hailar (Branch 543).[3]: 60, 84, 124, 310 


A medical school and research facility belonging to Unit 731 operated in the Shinjuku District of Tokyo during World War II. In 2006, Toyo Ishii—a nurse who worked at the school during the war—revealed that she had helped bury bodies and pieces of bodies on the school's grounds shortly after Japan's surrender in 1945. In response, in February 2011 the Ministry of Health began to excavate the site.[105]

While Tokyo courts acknowledged in 2002 that Unit 731 had been involved in biological warfare research, as of 2011[update] the Japanese government had made no official acknowledgment of the atrocities committed against test subjects, and rejected the Chinese government's requests for DNA samples to identify human remains (including skulls and bones) found near an army medical school.[106]

At Tokyo's Kyushu Imperial University in 1945 US POWs from a shot down B-29 were subjected to fatal medical experimentation.[107]

Surrender and immunity[edit]

Operations and experiments continued until the end of the war. Ishii had wanted to use biological weapons in the Pacific War since May 1944, but his attempts were repeatedly snubbed.

Destruction of evidence[edit]

With the coming of the Red Army in August 1945, the unit had to abandon their work in haste. Ministries in Tokyo ordered the destruction of all incriminating materials, including those in Pingfang. Potential witnesses, such as the 300 remaining prisoners were either gassed or fed poison while the 600 Chinese and Manchurian laborers were shot. Ishii ordered every member of the group to disappear and "take the secret to the grave".[108]Potassium cyanide vials were issued for use in case the remaining personnel were captured.

Skeleton crews of Ishii's Japanese troops blew up the compound in the final days of the war to destroy evidence of their activities, but many were sturdy enough to remain somewhat intact.

A photograph of the Unit 731 square building taken during its destruction in 1945

American grant of immunity[edit]

Among the individuals in Japan after its 1945 surrender was Lieutenant Colonel Murray Sanders, who arrived in Yokohama via the American ship Sturgess in September 1945. Sanders was a highly regarded microbiologist and a member of America's military center for biological weapons. Sanders' duty was to investigate Japanese biological warfare activity. At the time of his arrival in Japan he had no knowledge of what Unit 731 was.[64] Until Sanders finally threatened the Japanese with bringing the Soviets into the picture, little information about biological warfare was being shared with the Americans. The Japanese wanted to avoid prosecution under the Soviet legal system, so the next morning after he made his threat, Sanders received a manuscript describing Japan's involvement in biological warfare.[109] Sanders took this information to General Douglas MacArthur, who was the Supreme Commander of the Allied Powers responsible for rebuilding Japan during the Allied occupations. MacArthur struck a deal with Japanese informants:[110] He secretly granted immunity to the physicians of Unit 731, including their leader, in exchange for providing America, but not the other wartime allies, with their research on biological warfare and data from human experimentation.[6] American occupation authorities monitored the activities of former unit members, including reading and censoring their mail.[111] The Americans believed that the research data was valuable, and did not want other nations, particularly the Soviet Union, to acquire data on biological weapons.[112]

The Tokyo War Crimes Tribunal heard only one reference to Japanese experiments with "poisonous serums" on Chinese civilians. This took place in August 1946 and was instigated by David Sutton, assistant to the Chinese prosecutor. The Japanese defense counsel argued that the claim was vague and uncorroborated and it was dismissed by the tribunal president, Sir William Webb, for lack of evidence. The subject was not pursued further by Sutton, who was probably unaware of Unit 731's activities. His reference to it at the trial is believed to have been accidental.

Separate Soviet trials[edit]

Although publicly silent on the issue at the Tokyo Trials, the Soviet Union pursued the case and prosecuted twelve top military leaders and scientists from Unit 731 and its affiliated biological-war prisons Unit 1644 in Nanjing, and Unit 100 in Changchun, in the Khabarovsk War Crime Trials. Included among those prosecuted for war crimes, including germ warfare, was General Otozō Yamada, the commander-in-chief of the million-man Kwantung Army occupying Manchuria.

The trial of those captured Japanese perpetrators was held in Khabarovsk in December 1949. A lengthy partial transcript of the trial proceedings was published in different languages the following year by a Moscow foreign languages press, including an English-language edition.[113] The lead prosecuting attorney at the Khabarovsk trial was Lev Smirnov, who had been one of the top Soviet prosecutors at the Nuremberg Trials. The Japanese doctors and army commanders who had perpetrated the Unit 731 experiments received sentences from the Khabarovsk court ranging from two to 25 years in a Siberianlabor camp. The United States refused to acknowledge the trials, branding them communist propaganda.[114] The sentences doled out to the Japanese perpetrators were unusually lenient by Soviet standards, and all but one of the defendants returned to Japan by the 1950s (with the remaining prisoner committing suicide inside his cell). In addition to the accusations of propaganda, the US also asserted that the trials were to only serve as a distraction from the Soviet treatment of several hundred thousand Japanese prisoners of war; meanwhile, the USSR asserted that the US had given the Japanese diplomatic leniency in exchange for information regarding their human experimentation. The accusations of both the US and the USSR were true, and it is believed that the Japanese had also given information to the Soviets regarding their biological experimentation for judicial leniency.[115] This was evidenced by the Soviet Union building a biological weapons facility in Sverdlovsk using documentation captured from Unit 731 in Manchuria.[116]

Official silence under United States occupation[edit]

As above, under the American occupation the members of Unit 731 and other experimental units were allowed to go free. On 6 May 1947, Douglas MacArthur, as Supreme Commander of the Allied Forces, wrote to Washington that "additional data, possibly some statements from Ishii, can probably be obtained by informing Japanese involved that information will be retained in intelligence channels and will not be employed as 'war crimes' evidence".[6]

One graduate of Unit 1644, Masami Kitaoka, continued to do experiments on unwilling Japanese subjects from 1947 to 1956 while working for Japan's National Institute of Health Sciences. He infected prisoners with rickettsia and mental health patients with typhus.[117]Shiro Ishii, as the chief of the unit, was granted war crime immunity from the US occupation authorities, because of his provision of human experimentation research materials to the US. From 1948 to 1958, less than 5% of the documents were transferred onto microfilm and stored in the National Archives of the United States, before being shipped back to Japan.[118]

Post-occupation Japanese media coverage and debate[edit]

Japanese discussions of Unit 731's activity began in the 1950s, after the end of the American occupation of Japan. In 1952, human experiments carried out in Nagoya City Pediatric Hospital, which resulted in one death, were publicly tied to former members of Unit 731.[119] Later in that decade, journalists suspected that the murders attributed by the government to Sadamichi Hirasawa were actually carried out by members of Unit 731. In 1958, Japanese author Shūsaku Endō published the book The Sea and Poison about human experimentation, which is thought to have been based on a real incident.

The author Seiichi Morimura published The Devil's Gluttony (悪魔の飽食) in 1981, followed by The Devil's Gluttony: A Sequel in 1983. These books purported to reveal the "true" operations of Unit 731, but falsely attributed unrelated photos to the Unit, which raised questions about their accuracy.[120][121]

Also in 1981 appeared the first direct testimony of human vivisection in China, by Ken Yuasa. Since then many more in-depth testimonies have appeared in Japanese. The 2001 documentary Japanese Devils was composed largely of interviews with 14 members of Unit 731 who had been taken as prisoners by China and later released.[122]

Significance in postwar research of bio-warfare and medicine[edit]

There was consensus among US researchers in the postwar period that the human experimentation data gained was of little value to the development of American biological weapons and medicine. Postwar reports have generally regarded the data as "crude and ineffective", with one expert even deeming it "amateurish".[123] Harris speculates that the reason US scientists generally wanted to acquire it was due to the concept of forbidden fruit, believing that lawful and ethical prohibitions could affect the outcomes of their research.[124]

Official government response in Japan[edit]

See also: List of war apology statements issued by Japan

Unit 731 presents a special problem, since unlike Nazi human experimentation, which the United States publicly condemned, the activities of Unit 731 are known to the general public only from the testimonies of willing former unit members, and testimony cannot be employed to determine indemnity in this way.[citation needed]

Japanese history textbooks usually contain references to Unit 731, but do not go into detail about allegations, in accordance with this principle.[125][126]Saburō Ienaga's New History of Japan included a detailed description, based on officers' testimony. The Ministry for Education attempted to remove this passage from his textbook before it was taught in public schools, on the basis that the testimony was insufficient. The Supreme Court of Japan ruled in 1997 that the testimony was indeed sufficient and that requiring it to be removed was an illegal violation of freedom of speech.[127]

In 1997, the international lawyer Kōnen Tsuchiya filed a class action suit against the Japanese government, demanding reparations for the actions of Unit 731, using evidence filed by Professor Makoto Ueda of Rikkyo University. All Japanese court levels found that the suit was baseless. No findings of fact were made about the existence of human experimentation, but the decision of the court was that reparations are determined by international treaties and not by national court cases.[citation needed]

In August 2002, the Tokyo district court ruled for the first time that Japan had engaged in biological warfare. Presiding judge Koji Iwata ruled that Unit 731, on the orders of the Imperial Japanese Army headquarters, used bacteriological weapons on Chinese civilians between 1940 and 1942, spreading diseases including plague and typhoid in the cities of Quzhou, Ningbo, and Changde. However, he rejected the victims' claims for compensation on the grounds that they had already been settled by international peace treaties.[128]

In October 2003, a member of the House of Representatives of Japan filed an inquiry. Prime Minister Junichiro Koizumi responded that the Japanese government did not then possess any records related to Unit 731, but the government recognized the gravity of the matter and would publicize any records that were located in the future.[129] In April 2018, the National Archives of Japan released the names of 3,607 members of Unit 731, in response to a request by Professor Katsuo Nishiyama of the Shiga University of Medical Science.[130][131]


After WWII, the Office of Special Investigations created a watchlist of suspected Axis collaborators and persecutors who are banned from entering the United States. While they have added over 60,000 names to the watchlist, they have only been able to identify under 100 Japanese participants. In a 1998 correspondence letter between the DOJ and Rabbi Abraham Cooper, Eli Rosenbaum, director of OSI, stated that this was due to two factors. (1) While most documents captured by the US in Europe were microfilmed before being returned to their respective governments, the Department of Defense decided to not microfilm its vast collection of documents before returning them to the Japanese government. (2) The Japanese government has also failed to grant the OSI meaningful access to these and related records after the war, while European countries, on the other hand, have been largely cooperative,[132] the cumulative effect of which is that information pertaining to identifying these individuals is, in effect, impossible to recover.

In popular culture[edit]

Print media[edit]

  • The Narrow Road to the Deep North, a Booker Prize-winning 2014 novel by Australian writer Richard Flanagan, refers extensively to the atrocities committed by a doctor who served in Unit 731.
  • Forest Sea (Pol.Leśne morze) (1960), a novel by a Polish writer and educator Igor Newerly. The first book published outside Asia which refers to atrocities committed in the unit.
  • The Man Who Ended History: A Documentary (2011), a novella published in The Paper Menagerie book by American writer and Chinese translator Ken Liu: A scientific discovery allows a victim's descendant to go back in time to witness and learn the truth about the atrocities committed in the unit.
  • Tricky Twenty-Two, a novel in the Stephanie Plum series by Janet Evanovich, features as its antagonist a deranged biology professor who is obsessed with Unit 731 and is attempting to re-create the unit's bubonic plague dispersals.
  • The Solomon Curse, a novel in the Fargo Adventures series by Clive Cussler and Russell Blake, involves this unit in its plot, around secret human experimentation on the island of Guadalcanal.
  • The Grimnoire Series, an alternative-history series of novels by Larry Correia, has Unit 731 conducting brutal magical experiments on prisoners of the Japanese Imperium.
  • Setting Sun story form Hellblazer #142 by DC Comics, written by Warren Ellis and illustrated by Javier Pulido features a fictitious character who used to be a doctor in Unit 731 during the war and conducted experiments on humans.
  • In the manga My Hero Academia, a mad scientist who conducts experiments on humans to create a genetically-modified race was first introduced as Shiga Maruta. Because of the association with the Maruta project, it caused a major controversy, especially in China, where Tencent and Bilibili removed the manga from their platforms.[133] Both Weekly Shonen Jump magazine and the author Kohei Horikoshi issued individual apologizing statements on Twitter,[133] and the character name was changed in subsequent publications.[134]


There have been several films about the atrocities of Unit 731.

  • Through Gobi and Khingan (1981); Co-production of USSR, Mongolia, Eastern Germany. Miniseries (2 episodes).
  • The Sea and Poison (1986), Japan, directed by Kei Kumai
  • Men Behind the Sun (1988), China, directed by Tun Fei Mou
  • Unit 731: Laboratory of the Devil (1992), China, directed by Godfrey Ho
  • 731: Two Versions of Hell (2007), produced by James T. Hong; documentary about Unit 731 told from the Chinese and Japanese sides[135]
  • Philosophy of a Knife (2008), Russia, directed by Andrey Iskanov
  • Dead Mine (2012), Indonesia, directed by Steven Sheil and based in a fictionalized version of Unit 731
  • Wife of a Spy (2020), Japan, directed by Kiyoshi Kurosawa and won the Silver Lion Award for Best Director at the Venice Film Festival in 2020.
  • Cliff Walkers (2021), China, directed by Zhang Yimou


  • "The Breeding House" (1994), Bruce Dickinson. Segment of the CD-single Tears of the Dragon, describing the atrocities committed by Unit 731 and the immunity granted by the Americans to the physicians of the Unit
  • "Unit 731" (2009), American thrash metal band Slayer. Song on the album World Painted Blood, describing the events and atrocities that occurred at Unit 731
  • "Unit 731" (2011), Power electronic band Brandkommando
  • "And You Will Beg for Our Secrets" (2016), from the Anaal Nathrakh album The Whole of the Law, refers to Unit 731's activities and the US amnesty given in exchange for information resulting from the experiments carried out.
  • "The New Eternity" (2018), from the Silent Planet album When the End Began refers to Unit 731's human experimentation and other crimes against humanity.
  • "Maruta" (2009), South Korean metal band Sad Legend.


  • Unit 731 – Did the Emperor Know?. Television South documentary made in 1985 and first broadcast on the 13th of August.[136]
  • The X-Files episode "731" (1995). Former members of Unit 731 secretly continue their experiments on humans under control of a covert U.S. government agency.
  • ReGenesis episode "Let it burn" (2007). Outbreaks of anthrax and glanders are traced to World War II Japan.
  • Warehouse 13 episode "The 40th Floor" (2011). General Shirō Ishii's medal from Unit 731 simulated drowning when applied to a victim's skin.
  • Concrete Revolutio. The experimentation on superhumans by the Japanese and Americans is a parallel to Unit 731.
  • The Truth of Unit 731: Elite medical students and human experiments (2017). A NHK Documentary broadcast in 2017, including paper materials, recording tapes, and interviews to former members and doctors who have implemented experiments in 731 Unit.
  • In The Blacklist, the episode "General Shiro" is a reference to Shirō Ishii.
  • Link to part of a recorded telephone interview with Yoshimura Hisato.

Video games[edit]

  • In Call of Duty: Black Ops 3, The Zombies map included in the second DLC pack, "Zetsubou no Shima", is loosely inspired by Unit 731.
  • In the indie horror game, Spooky's Jumpscare Mansion, the unit 731 experiments are explicitly referenced multiple times in terms of Specimen 9 (specifically stated to be a survivor of the Unit 731 experiments), as well as the labelling of human bodies as "logs". -"I'm taking all those "logs" they keep throwing out, and I'm nailing them together..."

See also[edit]

Second Sino–Japanese War and Pacific War (World War II in the Pacific)[edit]

Other human experimentation[edit]


  1. ^The Japanese word butai is variously translated with military terms such as "unit", "detachment", "regiment" or "company".


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Unit 731

By Avani Sihra

In the 1930s-‘40s, the Japanese Empire committed atrocities across Asia, such as the Rape of Nanking. German crimes such as human medical testing committed in concentration camps tend to receive more attention than Japan’s crimes against humanity, as more research has been done and more historians have spent time looking back and studying these horrific acts. However, the Japanese too played a part in human medical testing in a secret project called Unit 731.

Begun in 1937, Unit 731, located in Harbin, China, was created with legitimate intentions by the Japanese government. Started as an agency to promote public health, Unit 731 was meant to conduct research that would benefit Japanese soldiers, such as learning more about the ways in which the human body can withstand hunger and thirst and fight diseases. Early experiments were conducted on volunteers who had signed consent waivers, giving personnel permission. However, as the war intensified, they changed their methods.

Although the 1925 Geneva Accords had banned the use of biological or chemical weapons in warfare, the Japanese nevertheless wanted to prepare for these types of warfare. As these types of experiments were naturally ones that most people would not volunteer to take part in, the Japanese decided to use prisoners of war as their test subjects. Unit 731's victims who were primarily Chinese and Russians, along with some Mongolians and Koreans.

The leader of the unit was Lieutenant General Shiro Ishii. Along with the other scientists he recruited, they experimented by infecting test subjects with different types of diseases to see how their bodies would respond to pathogens. As the Japanese destroyed most of the Unit’s records at the end of the war, little is known about the scientists who worked there.

Using the test subjects, the scientists injected different germs to see how they would react to one another in the human body, in an attempt to create new diseases. Referring to their victims as Maturas, or “wooden logs,” Japanese scientists would perform different types of procedures, such as vivisection, on live victims. Rats infected with the bubonic plague were released onto victims, with the intention of infecting the subjects so that they could be studied. Unit 731 was a place of torture that was, in the minds of many Unit 731 workers, a necessity in order to win the war.

Scientists in Unit 731 also experimented on their test subjects through pregnancy and rape. Male prisoners infected with syphilis would be told to rape female prisoners as well as male prisoners in order to see how syphilis spreads in the body. Women were involuntarily impregnated and then experiments were done on them to see how it affected the mother as well as the fetus. Sometimes the mother would be vivisected in order to see how the fetus was developing. 

Once it was clear that the Japanese were going to lose the war, unit workers destroyed much of the evidence of the experiments. Upon the formal surrender of the Japanese in August 1945, Unit 731 was officially terminated. The Japanese government did not admit to the wrongdoing committed by Unit 731 until very recently. The government did not acknowledge the atrocity until 1988, and even then, they did not apologize for what had happened. The project was highly secretive and much of the evidence had been destroyed; in addition, government officials who were aware of what happened in Unit 731 did not make their knowledge known to the public. Because of this lack of acknowledgment, the Chinese government took it upon themselves to spread awareness of the atrocities. In 1982, they established a museum in the same place where Unit 731 operated during the war.

Unlike some of the Nazi doctors who conducted experiments on prisoners and concentration camp inmates, none of those involved with the experiments at Unit 731 were ever punished for their crimes. Instead, after war’s end, many re-entered society and went on to have very successful careers in their fields. Americanforces, chiefly General Douglas MacArthur, decided not to put workers of Unit 731 on trial. MacArthur granted those involved immunity in exchange for the information they had gathered while doing their experiments. He believed that pursuing trials against these people would get in the way of the Americans receiving the medical information that had been documented from these experiments. Because of this decision, justice was never served.

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UNIT 731

Most of us heard about the horrible experiments on humans of the Nazis done by doctor Mengele. But the Nazis weren’t alone in conducting cruel experiments on humans.

One of the lesser known atrocities of the 20th century was committed by the Imperial Japanese Army’s Unit 731. Some of the details of this unit’s activities are still uncovered.

This webpage was set up to collect and organize the information known to date about Unit 731 and present it to anyone interested.

For 40 years, the horrific activities of “Unit 731” remained one the most closely guarded secrets of World War II. It was not until 1984 that Japan acknowledged what it had long denied – vile experiments on humans conducted by the unit in preparation for germ warfare.

Deliberately infected with plague, anthrax, cholera and other pathogens, an estimated 3,000 of enemy soldiers and civilians were used as guinea pigs. Some of the more horrific experiments included vivisection without anesthesia and pressure chambers to see how much a human could take before his eyes popped out.

Unit 731 was set up in 1938 in Japanese-occupied China with the aim of developing biological weapons. It also operated a secret research and experimental school in Shinjuku, central Tokyo. Its head was Lieutenant Shiro Ishii.

The unit was supported by Japanese universities and medical schools which supplied doctors and research staff. The picture now emerging about its activities is horrifying.

According to reports never officially admitted by the Japanese authorities, the unit used thousands of Chinese and other Asian civilians and wartime prisoners as human guinea pigs to breed and develop killer diseases.

Many of the prisoners, who were murdered in the name of research, were used in hideous vivisection and other medical experiments, including barbaric trials to determine the effect of frostbite on the human body.

To ease the conscience of those involved, the prisoners were referred to not as people or patients but as “Maruta”, or wooden logs. Before Japan’s surrender, the site of the experiments was completely destroyed, so that no evidence is left.

Then, the remaining 400 prisoners were shot and employees of the unit had to swear secrecy. The mice kept in the laboratory were then released, which could have cost the lives of 30,000 people, since the mice were infected with the bubonic plague, and they spread the disease.

Few of those involved with Unit 731 have admitted their guilt.

Some caught in China at the end of the war were arrested and detained, but only a handful of them were prosecuted for war crimes.

In Japan, not one was brought to justice. In a secret deal, the post-war American administration gave them immunity for prosecution in return for details of their experiments.

Some of the worst criminals, including Hisato Yoshimura, who was in charge of the frostbite experiments, went on to occupy key medical and other posts in public and private sectors.

UNIT 731 Japanese Human Experimentation - The Aftermath - NEW HD 2018

United States Responses to Japanese Wartime Inhuman Experimentation after World War II: National Security and Wartime Exigency


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Japan section 731

Unit 731: Japan discloses details of notorious chemical warfare division

Japan has disclosed the names of thousands of members of Unit 731, a notorious branch of the imperial Japanese army that conducted lethal experiments on Chinese civilians in the 1930s and 40s as it sought to develop chemical and biological weapons.

The country’s national archives passed on the names of 3,607 people in response to a request by Katsuo Nishiyama, a professor at Shiga University of Medical Science, in a move that could reignite the public debate over Japanese atrocities committed in occupied China before and during the second world war.

“This is the first time that an official document showing the real names of almost all members of Unit 731 has been disclosed,” Nishiyama told the Mainichi Shimbun newspaper. “The list is important evidence that supports testimony by those involved. Its discovery will be a major step toward unveiling concealed facts.”

The document lists members of the Kwantung army’s Epidemic Prevention and Water Purification Department – the unit’s official name – and is dated 1 January 1945. It includes the names, ranks and contact details of more than 1,000 army medics, as well as dozens of doctors, surgeons, nurses and engineers.

Japan reluctantly acknowledged the unit’s existence in the late 1990s, but has refused to discuss its activities. Instead, accounts of the unit’s activities have been built around testimony from former members, photographs and documentary evidence.

In 2006, Toyo Ishii, a former nurse, said she had helped bury the remains of victims of Japan’s biological warfare programme at a site in Tokyo, as US forces moved into the Japanese capital at the end of the second word war. Ishii said she and her colleagues had been ordered to bury numerous corpses, bones and body parts following Japan’s surrender in August 1945.

Other accounts indicate that similar experiments took place in other parts of Asia. In 2006, Akira Makino, a former doctor, said he had been ordered to conduct experiments on condemned men while stationed on the island of Mindanao in the Philippines.

Formed in the mid-1930s in Harbin, north-eastern China, Unit 731 conducted lethal experiments on an estimated 3,000 prisoners, who were mostly Chinese and Korean.

According to historical accounts, male and female prisoners, named “logs” by their torturers, were subjected to vivisection without anaesthesia after they had been deliberately infected with diseases such as typhus and cholera. Some had limbs amputated or organs removed.

As Japan headed towards defeat in the summer of 1945, the unit’s leader, Lt Gen Shiro Ishii, forbade researchers from discussing their work and ordered the demolition of the unit’s Harbin headquarters.

At the end of the war, US authorities secretly granted unit officials immunity from prosecution in return for access to their research. Several former Unit 731 officials went on to have successful careers in medicine, academia and business.

Nishiyama reportedly plans to publish the list online to encourage historians to conduct further studies into the unit.

Japanese Unit 731: A history of war-time horror

As the 76th anniversary of Japan's unconditional surrender in World War Two (WWII) falls on Sunday, a Chinese museum is displaying for the first time new items that belonged to the former Japanese Unit 731.

Unit 731 was a top-secret biological and chemical warfare research base established in the northeastern Chinese city of Harbin. The facility was considered the nerve center of Japanese biological warfare in China and Southeast Asia during WWII – a notorious branch of the Japanese army that carried out human experimentation and large-scale germ warfare.

At least 3,000 people were used for human experimentation by Unit 731 and more than 300,000 people in China were killed by Japan's biological weapons.

The Museum of Evidence of War Crimes by Japanese Army Unit 731 in Harbin occupies 11,000 square meters inside the remnants of Unit 731. It was built to mourn the loss of life and humanity within its walls. 

It exhibits photos and first-hand testimonies of the imperialist Japanese army's so called "research" and use of germ warfare and experiments on humans, as well as the final war-crimes trial.

For most people in Asia, August 15 is a special date that will never be erased from their memory. The war of aggression initiated by Japan brought untold sufferings to the people in Asia. China alone suffered 35 million casualties and $600 billion in economic losses in the War of Resistance against Japanese Aggression.

(With input from Xinhua)

(Cover: The exhibition hall of evidences of crime committed by Unit 731 of the Japanese Imperial Army in Harbin, Heilongjiang Province, China. /CFP)


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Unmasking Horror -- A special report.; Japan Confronting Gruesome War Atrocity

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He is a cheerful old farmer who jokes as he serves rice cakes made by his wife, and then he switches easily to explaining what it is like to cut open a 30-year-old man who is tied naked to a bed and dissect him alive, without anesthetic.

"The fellow knew that it was over for him, and so he didn't struggle when they led him into the room and tied him down," recalled the 72-year-old farmer, then a medical assistant in a Japanese Army unit in China in World War II. "But when I picked up the scalpel, that's when he began screaming.

"I cut him open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony. He made this unimaginable sound, he was screaming so horribly. But then finally he stopped. This was all in a day's work for the surgeons, but it really left an impression on me because it was my first time."

Finally the old man, who insisted on anonymity, explained the reason for the vivisection. The Chinese prisoner had been deliberately infected with the plague as part of a research project -- the full horror of which is only now emerging -- to develop plague bombs for use in World War II. After infecting him, the researchers decided to cut him open to see what the disease does to a man's inside. No anesthetic was used, he said, out of concern that it might have an effect on the results.

That research program was one of the great secrets of Japan during and after World War II: a vast project to develop weapons of biological warfare, including plague, anthrax, cholera and a dozen other pathogens. Unit 731 of the Japanese Imperial Army conducted research by experimenting on humans and by "field testing" plague bombs by dropping them on Chinese cities to see whether they could start plague outbreaks. They could.

A trickle of information about the program has turned into a stream and now a torrent. Half a century after the end of the war, a rush of books, documentaries and exhibitions are unlocking the past and helping arouse interest in Japan in the atrocities committed by some of Japan's most distinguished doctors.

Scholars and former members of the unit say that at least 3,000 people -- by some accounts several times as many -- were killed in the medical experiments; none survived.

No one knows how many died in the "field testing." It is becoming evident that the Japanese officers in charge of the program hoped to use their weapons against the United States. They proposed using balloon bombs to carry disease to America, and they had a plan in the summer of 1945 to use kamikaze pilots to dump plague-infected fleas on San Diego.

The research was kept secret after the end of the war in part because the United States Army granted immunity from war crimes prosecution to the doctors in exchange for their data. Japanese and American documents show that the United States helped cover up the human experimentation. Instead of putting the ringleaders on trial, it gave them stipends.

The accounts are wrenching to read even after so much time has passed: a Russian mother and daughter left in a gas chamber, for example, as doctors peered through thick glass and timed their convulsions, watching as the woman sprawled over her child in a futile effort to save her from the gas. The Origins Ban on Weapon Entices Military

Japan's biological weapons program was born in the 1930's, in part because Japanese officials were impressed that germ warfare had been banned by the Geneva Convention of 1925. If it was so awful that it had to be banned under international law, the officers reasoned, it must make a great weapon.

The Japanese Army, which then occupyied a large chunk of China, evicted the residents of eight villages near Harbin, in Manchuria, to make way for the headquarters of Unit 731. One advantage of China, from the Japanese point of view, was the availability of research subjects on whom germs could be tested. The subjects were called marutas, or logs, and most were Communist sympathizers or ordinary criminals. The majority were Chinese, but many were Russians, expatriates living in China.

Takeo Wano, a 71-year-old former medical worker in Unit 731 who now lives here in the northern Japanese city of Morioka, said he once saw a six-foot-high glass jar in which a Western man was pickled in formaldehyde. The man had been cut into two pieces, vertically, and Mr. Wano guesses that he was Russian because there were many Russians then living in the area.

The Unit 731 headquarters contained many other such jars with specimens. They contained feet, heads, internal organs, all neatly labeled. "I saw samples with labels saying 'American,' 'English' and 'Frenchman,' but most were Chinese, Koreans and Mongolians," said a Unit 731 veteran who insisted on anonymity. "Those labeled as American were just body parts, like hands or feet, and some were sent in by other military units."

There is no evidence that Americans were among the victims in the Unit 731 compound, although there have been persistent but unproven accusations that American prisoners of war in Mukden (now Shenyang) were subject to medical experimentation.

Medical researchers also locked up diseased prisoners with healthy ones, to see how readily various ailments would spread. The doctors locked others inside a pressure chamber to see how much the body can withstand before the eyes pop from their sockets.

Victims were often taken to a proving ground called Anda, where they were tied to stakes and bombarded with test weapons to see how effective the new technologies were. Planes sprayed the zone with a plague culture or dropped bombs with plague-infested fleas to see how many people would die.

The Japanese armed forces were using poison gas in their battles against Chinese troops, and so some of the prisoners were used in developing more lethal gases. One former member of Unit 731 who insisted on anonymity said he was taken on a "field trip" to the proving ground to watch a poison gas experiment.

A group of prisoners were tied to stakes, and then a tank-like contraption that spewed out gas was rolled toward them, he said. But at just that moment, the wind changed and the Japanese observers had to run for their lives without seeing what happened to the victims.

The Japanese Army regularly conducted field tests to see whether biological warfare would work outside the laboratory. Planes dropped plague-infected fleas over Ningbo in eastern China and over Changde in north-central China, and plague outbreaks were later reported.

Japanese troops also dropped cholera and typhoid cultures in wells and ponds, but the results were often counterproductive. In 1942 germ warfare specialists distributed dysentery, cholera and typhoid in Zhejiang Province in China, but Japanese soldiers became ill and 1,700 died of the diseases, scholars say.

Sheldon H. Harris, a historian at California State University in Northridge, estimates that more than 200,000 Chinese were killed in germ warfare field experiments. Professor Harris -- author of a book on Unit 731, "Factories of Death" (Routledge, 1994) -- also says plague-infected animals were released as the war was ending and caused outbreaks of the plague that killed at least 30,000 people in the Harbin area from 1946 through 1948.

The leading scholar of Unit 731 in Japan, Keiichi Tsuneishi, is skeptical of such numbers. Professor Tsuneishi, who has led the efforts in Japan to uncover atrocities by Unit 731, says that the attack on Ningbo killed about 100 people and that there is no evidence of huge outbreaks of disease set off by field trials. The Tradeoff Knowledge Gained At Terrible Cost

Many of the human experiments were intended to develop new treatments for medical problems that the Japanese Army faced. Many of the experiments remain secret, but an 18-page report prepared in 1945 -- and kept by a senior Japanese military officer until now -- includes a summary of the unit's research. The report was prepared in English for American intelligence officials, and it shows the extraordinary range of the unit's work.

Scholars say that the research was not contrived by mad scientists, and that it was intelligently designed and carried out. The medical findings saved many Japanese lives.

For example, Unit 731 proved scientifically that the best treatment for frostbite was not rubbing the limb, which had been the traditional method, but rather immersion in water a bit warmer than 100 degrees -- but never more than 122 degrees.

The cost of this scientific breakthrough was borne by those seized for medical experiments. They were taken outside in freezing weather and left with exposed arms, periodically drenched with water, until a guard decided that frostbite had set in. Testimony from a Japanese officer said this was determined after the "frozen arms, when struck with a short stick, emitted a sound resembling that which a board gives when it is struck."

A booklet just published in Japan after a major exhibition about Unit 731 shows how doctors even experimented on a three-day-old baby, measuring the temperature with a needle stuck inside the infant's middle finger.

"Usually a hand of a three-day-old infant is clenched into a fist," the booklet says, "but by sticking the needle in, the middle finger could be kept straight to make the experiment easier." The Scope Other Experiments On Humans

The human experimentation did not take place just in Unit 731, nor was it a rogue unit acting on its own. While it is unclear whether Emperor Hirohito knew of the atrocities, his younger brother, Prince Mikasa, toured the Unit 731 headquarters in China and wrote in his memoirs that he was shown films showing how Chinese prisoners were "made to march on the plains of Manchuria for poison gas experiments on humans."

In addition, the recollections of Dr. Ken Yuasa, 78, who still practices in a clinic in Tokyo, suggest that human experimentation may have been routine even outside Unit 731. Dr. Yuasa was an army medic in China, but he says he was never in Unit 731 and never had contact with it.

Nevertheless, Dr. Yuasa says that when he was still in medical school in Japan, the students heard that ordinary doctors who went to China were allowed to vivisect patients. And sure enough, when Dr. Yuasa arrived in Shanxi Province in north-central China in 1942, he was soon asked to attend a "practice surgery."

Two Chinese men were brought in, stripped naked and given general anesthetic. Then Dr. Yuasa and the others began practicing various kinds of surgery: first an appendectomy, then an amputation of an arm and finally a tracheotomy. After 90 minutes, they were finished, so they killed the patient with an injection.

When Dr. Yuasa was put in charge of a clinic, he said, he periodically asked the police for a Communist to dissect, and they sent one over. The vivisection was all for practice rather than for research, and Dr. Yuasa says they were routine among Japanese doctors working in China in the war.

In addition, Dr. Yuasa -- who is now deeply apologetic about what he did -- said he cultivated typhoid germs in test tubes and passed them on, as he had been instructed to do, to another army unit. Someone from that unit, which also had no connection with Unit 731, later told him that the troops would use the test tubes to infect the wells of villages in Communist-held territory. The Plans Taking the War To U.S. Homeland

In 1944, when Japan was nearing defeat, Tokyo's military planners seized on a remarkable way to hit back at the American heartland: they launched huge balloons that rode the prevailing winds to the continental United States. Although the American Government censored reports at the time, some 200 balloons landed in Western states, and bombs carried by the balloons killed a woman in Montana and six people in Oregon.

Half a century later, there is evidence that it could have been far worse; some Japanese generals proposed loading the balloons with weapons of biological warfare, to create epidemics of plague or anthrax in the United States. Other army units wanted to send cattle-plague virus to wipe out the American livestock industry or grain smut to wipe out the crops.

There was a fierce debate in Tokyo, and a document discovered recently suggests that at a crucial meeting in late July 1944 it was Hideki Tojo -- whom the United States later hanged for war crimes -- who rejected the proposal to use germ warfare against the United States.

At the time of the meeting, Tojo had just been ousted as Prime Minister and chief of the General Staff, but he retained enough authority to veto the proposal. He knew by then that Japan was likely to lose the war, and he feared that biological assaults on the United States would invite retaliation with germ or chemical weapons being developed by America.

Yet the Japanese Army was apparently willing to use biological weapons against the Allies in some circumstances. When the United States prepared to attack the Pacific island of Saipan in the late spring of 1944, a submarine was sent from Japan to carry biological weapons -- it is unclear what kind -- to the defenders.

The submarine was sunk, Professor Tsuneishi says, and the Japanese troops had to rely on conventional weapons alone.

As the end of the war approached in 1945, Unit 731 embarked on its wildest scheme of all. Codenamed Cherry Blossoms at Night, the plan was to use kamikaze pilots to infest California with the plague.

Toshimi Mizobuchi, who was an instructor for new recruits in Unit 731, said the idea was to use 20 of the 500 new troops who arrived in Harbin in July 1945. A submarine was to take a few of them to the seas off Southern California, and then they were to fly in a plane carried on board the submarine and contaminate San Diego with plague-infected fleas. The target date was to be Sept. 22, 1945.

Ishio Obata, 73, who now lives in Ehime prefecture, acknowledged that he had been a chief of the Cherry Blossoms at Night attack force against San Diego, but he declined to discuss details. "It is such a terrible memory that I don't want to recall it," he said.

Tadao Ishimaru, also 73, said he had learned only after returning to Japan that he had been a candidate for the strike force against San Diego. "I don't want to think about Unit 731," he said in a brief telephone interview. "Fifty years have passed since the war. Please let me remain silent."

It is unclear whether Cherry Blossoms at Night ever had a chance of being carried out. Japan did indeed have at least five submarines that carried two or three planes each, their wings folded against the fuselage like a bird.

But a Japanese Navy specialist said the navy would have never allowed its finest equipment to be used for an army plan like Cherry Blossoms at Night, partly because the highest priority in the summer of 1945 was to defend the main Japanese islands, not to launch attacks on the United States mainland.

If the Cherry Blossoms at Night plan was ever serious, it became irrelevant as Japan prepared to surrender in early August 1945. In the last days of the war, beginning on Aug. 9, Unit 731 used dynamite to try to destroy all evidence of its germ warfare program, scholars say. The Aftermath No Punishment, Little Remorse

Partly because the Americans helped cover up the biological warfare program in exchange for its data, Gen. Shiro Ishii, the head of Unit 731, was allowed to live peacefully until his death from throat cancer in 1959. Those around him in Unit 731 saw their careers flourish in the postwar period, rising to positions that included Governor of Tokyo, president of the Japan Medical Association and head of the Japan Olympic Committee.

By conventional standards, few people were more cruel than the farmer who as a Unit 731 medic carved up a Chinese prisoner without anesthetic, and who also acknowledged that he had helped poison rivers and wells. Yet his main intention in agreeing to an interview seemed to be to explain that Unit 731 was not really so brutal after all.

Asked why he had not anesthetized the prisoner before dissecting him, the farmer explained: "Vivisection should be done under normal circumstances. If we'd used anesthesia, that might have affected the body organs and blood vessels that we were examining. So we couldn't have used anesthetic."

When the topic of children came up, the farmer offered another justification: "Of course there were experiments on children. But probably their fathers were spies."

"There's a possibility this could happen again," the old man said, smiling genially. "Because in a war, you have to win."


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