10 things to know about the Japanese Army’s Unit 731

Patricia Hului

Unit 731’s official name was ‘Epidemic Prevention and Water Purification Department of the Kwantung Army’ but their actual work had nothing to do with safeguarding health and security.

This biological and chemical warfare research development unit of the Imperial Japanese Army actually started epidemics and polluted rivers with human remains.

Based at the Pingfang district of Harbin, Northeast China, the unit undertook deadly human experimentation during the Second Sino-Japanese War (1937-1945) of World War II (WWII).

Unit 731 was commanded by General Shiro Ishii, a combat medic officer in the Kwantung Army.

They routinely conducted tests on human beings who the members of Unit 731 referred to as ‘maruta’, or ‘logs’ in Japanese.

The majority of victims were Chinese with small percentage of Russian, Mongolian and Korean. They also did human experiments of European, American, Indian, Australian and New Zealander prisoners of war (POWs) who were imprisoned at Mukden camp.

It is estimated that up to half a million people were killed by Unit 731 and its related programs.

The Unit 731 complex. Two prisons are hidden in the center of the main building. Credit: Copyright expired

Here are 10 things to know about the Imperial Japanese Army’s notorious chemical warfare department Unit 731:

1.Frostbite experiments on victims including babies

Yoshimura Hisato was a lecturer at Kyota Imperial University Faculty of Medicine before he joined Unit 731 in 1938.

At the Khabarovsk War Trial in 1949, a sergeant major from Military Police at Unit 731 testified on Yoshimura’s experiments on frostbite.

He said, “When I walked into the prison laboratory, five Chinese experimentees were sitting on a long form [bench]; two of these Chinese had no fingers at all, their hands were black; in those of three others the bones were visible. They had fingers, but they were only bones. Yoshimura told me that this was the result of freezing experiments.”

After the war had ended, Yoshimura managed to escape from Manchuria, received war crime immunity, returned to university and finally became the president of Kyoto Prefectural University of Medicine.

Right up to the end, Yoshimura denied having performed these experiments although his own published scientific papers proved otherwise.

The papers revealed that not only male subjects were experimented on, but women, children and even a 3-day-old baby.

The frostbite experiment was done by chilling selected body parts to nearly 0 degrees Celsius with ice water.

2. How Unit 731 devised a method for transmission of syphilis between victims

The Japanese army wanted to develop a cure for syphilis since many of their soldiers had been infected through rape or intercourse with comfort women. But first, they wanted to study how syphilis was transmitted. Initial attempts to study the transmission of syphilis through injections were abandoned due to the absence of real results. The doctors of Unit 731 then orchestrated forced sex between infected and non infected prisoners to transmit the disease.

Nishino Rumiko, who interviewed former unit members of Unit 731, recounted during her lecture on “Unit 731 and Comfort Women”: “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 cover the body with only eyes and mouth visible, handled the tests. A male and female, on inflicted with syphilis, would be brought together in a cell and forced into sex with each others. It was made clear that anyone resisting would be shot.”

3.The testimony of a former medical assistant in Unit 731

Speaking to the New York Times in 1996, a former medical assistant in Unit 731 anonymously revealed what happened during his first vivisection.

“The fellow knew that it was over for him so he did not 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.”

4.A doctor of Unit 731 described his first vivisection in a 2007 interview with The Japan Times

Dr Ken Yuasa (1916-2010), a wartime surgeon, was one of at least 1,000 other doctors and nurses who conducted vivisections – surgeries conducted for experimental purposes on live organisms – under Unit 731.

In his interview with The Japan Times, he describes how took part in his first vivisection in March 1942 at an army hospital in Changzhi (formerly Luan) in Shanxi Province, China.

He tells that there were two operating tables surrounded by some 20 people, including medics, surgeons and hospital directors.

The victims were Chinese prisoners; one tall, brawny young man and an older man who may have been a farmer. Both the victims were handcuffed and waiting beside the tables.

The doctors started the vivisection with an appendectomy. Yuasa revealed that it took the doctors three incisions to locate and cut out the organ because it was ‘perfectly healthy’.

He then proceeded to perform a tracheotomy which caused bright red blood to gush out and spill on the floor.

Yuasa admitted that he was ‘impelled by interest’ so he amputated the prisoner’s right forearm.

The older patient was dead by the end of the procedures but the young prisoner was still breathing. Yuasa then injected anesthetic into his vein and executed him. Later, the victims were dumped in a hole near the hospital.

Yuasa had not realised the depth of his atrocious acts under Unit 731 until much later when he became a prisoner of the People’s Liberation Army of China, and was instructed to confess his acts in writing. After receiving a letter from the vivisection victim’s mother sometime later, reality struck. Once he returned to Japan, he went on to disclose and reveal these gruesome wartime acts until his death in 2010 so that these kinds of atrocities would never happen again.

5.Cruel experiment on mother-child relationship

In order to test the bonds between mother and her child, the doctors of Unit 731 implemented a cruel deadly experiment on the pair.

One of the experiments had a Russian mother and daughter left in a gas chamber.

Then the doctors peered through the thick glass and timed their convulsions, watching as the woman sprawled over her child in a futile effort to save her from the gas.

6.Experimenting on American Prisoners of War (POWs)

American POWs were not exempt from these cruel and harsh experiments. Besides live vivisections, American PoWs had to endure having parts of the livers removed to see if they could survive. Another experiment saw a prisoner getting drilled through his skull see if epilepsy could be cured by the removal of part of the brain. Yet another testimony told the story of how they injected one anesthetised prisoner with seawater to see if it could replace sterile saline solution.

7.Victims were exposed to bacteria through deliberate bombing

Speaking of American POWs, the survivors and their families used the Freedom of Information Act to extract from the Pentagon formerly top secret documents on Mukden POW camp.

One of the documents recounted how 20 Manchurians were tied to poles or forced to sit on the ground near a bomb filled with bacteria.

Then, the bomb exploded sending plague bacilli and anthrax bacilli into their bodies through wounds.

The document stated, “The wounded were kept in the laboratory until the symptoms of the disease appeared and when they were taken ill, they were given medical treatment and their cases were studied but most of them died in agony.”

8.The attack on civilians through germ warfare

One of the survivors of the germ warfare, Wang Juhua revealed in a 2005 interview how the attack impacted her life.

Recalling the time when she first realised that her village was attacked, she said, “I went out to feed the cattle, and I walked through the grassland. When I came back, I felt my legs itching and I scratched them. Small red dots appeared on my legs and then became blisters.”

Wang was just 8 years old at the time.

It is estimated 250,000 people were killed when Japan launched its germ-warfare experiments during its military occupation of eastern and northern China.

The one responsible for these experiments was none other than Unit 731.

They created lethal packages of fleas, wheat grain, rice and beans, all infected with deadly pathogens such as anthrax, cholera, typhoid, dysentery and bubonic plaque.

After that, they dropped all these bags from airplanes over Chinese villages. Those who survived continued to live in miserable conditions like Wang who had to live with rotting legs.

9.There are active branches of Unit 731 throughout China and Southeast Asia including Malaysia

The breeding grounds of these deadly pathogens were at the branches of Unit 731 located throughout China and Southeast Asia.

Researcher Lim Shaobin learned from Japanese WWII documents that Singapore was serving as a base in order to transport rats and fleas to Malaya.

Then in Malaya, they were transferred to Tampoi Mental Hospital in Johor and a secondary school at Kuala Pisa near Kuala Lumpur. They were also sent to a facility in Bandung, Indonesia.

Little would Malaysians today know that Malaya was Unit 731’s largest breeding ground outside of Japan and China. The unit’s research found that rat fleas thrived in Malaysians’ temperature and humidity.

The fleas were made to feed on the blood and organs of rats that had died of bubonic plague. Then, millions of these fleas were taken in big glass jars to China.

Other units under the Epidemic Prevention and Water Purification Department like Unit 9420 even sent a supply of rodents from Tokyo to Singapore to supplement the local population of rats.

10.Wiping out the existence of Unit 731

Three days after Unit 731 members heard a broadcast newsflash about the Soviet invasion, they were all ordered to destroy the evidence of the existence of their unit.

A former Unit 731 personnel Naoji Uezono revealed, “First of all the marutas were killed. Then their bodies were put in the incinerator. The specimens taken from human bodies were also put in but there were so many that they just wouldn’t burn. So we took them down to the Sungari river and dumped them in.”

Some of the bodies were thrown into the courtyard pit, covered with heavy fuel oil and set alight.

The bones that remained were collected, put in straw bags and dumped in the river.

Originally, General Shiro Ishii ordered every member of Unit 731 along with the nearby villagers to commit suicide, to the extent of issuing everyone vials of poison.

However, his idea was strongly opposed by Unit 731’s research chief Major-General Hitoshi Kikuchi.

Finally, Ishii ordered them never speak of their military past for the rest of their lives and never contact each other again.

After the war, the researchers involved in Unit 731 were secretly given immunity by the US in exchange for the data they gathered through human experimentation.