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The Inherited “Results” of the Imperial Japanese Army’s Experiments on Human Beings

Thursday 14 September 2023, by Yong-hui Hong

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On August 21, NHK (Japan Broadcasting Corporation) reported that a rare document listing the names and ranks of members of the Imperial Japanese Army’s notorious wartime Unit 731 (the Epidemic Prevention and Water Purification Department of the Kwantung Army) had been discovered in Tokyo. It is the first time for such a record which include details about the organization’s personnel and organizational structure. These official documents were marked in red as “military secret” in red and will provide important basic data for clarifying the actual situation of Unit 731 in the future. Few documents related to Unit 731’s wartime research on biological and other weapons were found because the Imperial Japanese Army ordered to dispose of all related documents at the end of the war. What should not have been left behind was miraculously discovered.

After the Second World War, the doctors in Unit 731 were granted war criminal immunity in exchange for providing research data to the US. [1] And those involved have been tight-lipped about Unit 731. However, after the 1980s, the subordinates of General Shiro Ishii (commander of Unit 731) and former military doctors who had served in the army finally began to testify publicly about Unit 731. In recent years, related documents have gradually been discovered in other countries such as China, Russia and the US. This has led to significant progress in the investigation of Unit 731. However, the Japanese government, while acknowledging the existence of Unit 731, has yet to admit that human experiments were conducted. Nor has the Japanese government issued an apology. In the northeastern part of China, a large number of the abandoned chemical weapons left behind by the former Japanese army are still buried. On the other hand, the medical community in Japan, where many members of Unit 731 found employment after the war, has remained silent on the issue.

Historical background and formation of Unit 731

The Mukden Incident occurred in September 1931. The Kwantung Army [2] detonated dynamite near a railroad line owned by Japanese South Manchuria Railway near Mukden. The Imperial Japanese Army accused Chinese dissidents of this act and launched a full-scale invasion that led to the occupation of Manchuria. In 1932, the year after the Mukden Incident, the State of Manchuria was proclaimed. It was generally regarded as a puppet state of the Japanese Empire in northeastern China. In 1932, General Shiro Ishii, who wanted to establish an institution to prepare for germ warfare, was put in charge of the Army Epidemic Prevention Research Laboratory. The following year, in 1933, a research facility was established in Tokyo. In addition, a full-scale biological weapons testing and production facility was to be built in Manchuria. In 1933, a secret unit, the Togo Unit, was established on the outskirts of Harbin in northeastern China. The secret unit became an official unit of the Kwantung Army in 1936. And in 1937, the Imperial Japanese Army caused the Marco Polo Bridge Incident and launched an all-out war of aggression against China. Meanwhile, the Kwantung Army built a facility in the Pingfang district on the outskirts of Harbin City to test and produce biological weapons. And the Kwantung Army subsequently established related facilities throughout northeastern China. In 1941, the Pingfang district unit was renamed UNIT 731. Unit 731 was part of an organization created by General Shiro Ishii, known as “Ishii’s Organization”. The organization was supported by huge national budget.

The reality of human experimentation

Within the Unit 731 facility, a prison was set up to confine people (called “logs”) for human experimentation. In the Pingfang district alone, more than 3,000 people were killed in human experiments to develop biological weapons. Most of the victims were Chinese and Korean. Other victims of human experimentation included Russians and Mongolians. Not only in China, but also in Southeast Asia, human experiments were conducted as a part of medical training until 1945 [3]. [3] Tsuneishi Keiichi, a Japanese scholar of the history and theory of science, described in his book the reality of the human experiments that were allegedly conducted in Unit 731 [4]:

  • - Using the human body as a training platform for surgery
  • - Experiments on infectious diseases: living people were deliberately infected with germs such as pest, typhus, and cholera to see the effects of infectiousness. After infection, these people were dissected alive.
  • - Other human experiments: Human experiments for the development of vaccines and therapies.

Unit 731 and its affiliated units (Unit 1644 and Unit 100, among others) were involved in research on biological weapons, development and experimental deployment of epidemic-creating biowarfare weapons in assaults against the Chinese people. Unit 100 also experimented with toxic gas. Plague-infected fleas were spread by low-flying airplanes over Chinese cities. [5] Since the facilities of the Ishii’s Organization that made up Unit 731 were designed for thorough human experimentation and killing, there were no survivors from the human experiments. The biological weapons developed by Unit 731 were used in the military operations such as the Nomonhan Incident (1939) and the attack on Ningbo (1940) as the “results” of the human experiments.

Members of Unit 731 after the war

After the former Soviet Union entered the war in 1945, General Shiro Ishii worked hard to cover up the development of biological weapons and human experimentation. They killed all living “logs” and burned all records of biological weapons development. And they destroyed their headquarters in Harbin City and blew up their experimental facility. The Imperial Japanese Army had abandoned their chemical weapons, which were dumped into rivers or buried. Most of the abandoned chemical weapons in China, estimated at about 700,000, are buried in the Jilin Province. [6] At the same time, the members of Unit 731 quickly returned to Japan on a special train [7]. [7]

After the surrender of the Japanese Empire in World War II, the US began to investigate Unit 731. However, it was not an investigation of war crimes, but of the “results” of the development of biological weapons. The US interrogated the head of Unit 731, General Shiro Ishii, and other members. However, during this interrogation, it was confirmed several times that they would not be charged with war crimes. The former Soviet Union proposed to the US to share the biological weapons technologies between the two countries. But the US rejected the proposal. In exchange for access to the technologies, the US authorities secretly granted immunity from prosecution to General Shiro Ishii and others involved in Unit 731. The US condemned the Nazis doctors at the Nuremberg Trials. On the other hand, the US had chosen a different path of collaboration with war criminals regarding mass murder for the development of biological weapons in Unit 731. This was due to the US policy of prioritizing its own national interests over justice. The US monopolized the “results” of Unit 731’s human experiments for later use in the Korean War. The war criminals were eventually able to escape prosecution because China was in a state of civil war and the joint investigation by the US, the former Soviet Union, and China was made difficult by the Cold War between East and West.

War Crimes: What was covered up

Many doctors and researchers involved in human experimentation at Unit 731 were never charged with a crime. After the war, they went on to hold important positions in research institutes and corporations in Japan. Many of them became prominent doctors in the Japanese medical community after the war. For example, leaders of the National Institute of Health of Japan (now the National Institute of Infectious Diseases) which was founded in 1947 and of the Institute of Medical Science at the University of Tokyo. The Japanese medical community, which contributed to the wartime genocide in China through human experimentation during the war, also covered up the past. At the same time, its structural constitution was inherited unchanged. Unit 731 included some of the leading experts in dried plasma research.

One of them founded the Japan Blood Bank in 1951 to produce dried plasma. The Japan Blood Bank made huge profits during the Korean War by selling dried plasma and other technologies developed by Unit 731 to the US military. The company was renamed Green Cross Corporation in 1964. [8] Green Cross Corporation’s technology was recognized as world-class, inheriting the “results of human experimentation by Unit 731”. After that, Green Cross Corporation imported a large amount of plasma from the US. However, the plasma was contaminated with HIV. In 1982, the US Centers for Disease Control and Prevention (CDC) pointed out the risk of AIDS transmission through unheated blood products. [9] And in December of the same year, Green Cross Corporation was informed of the fact of AIDS infection through blood in the US. However, the company did not stop importing plasma. As a result, thousands of people in Japan, mostly hemophiliacs, became infected with HIV and more than 400 died. [10] Even after 1982, when the safety of unheated blood products was questioned internationally, unheated blood products were offered to hemophiliacs as if they were human experiments. It was as if the ghosts of Unit 731’s experimental disposition were reappearing.

After the Second World War, the 3,000 victims of the living “logs” massacre were resurrected as thousands of victims of the tainted blood scandal in Japan. In Germany, the medical science of the Nazi era was consistently evaluated and criticized. The lessons were incorporated into the education of medical students. On the other hand, the Japanese medical community, which was fully involved in Unit 731 and germ warfare during the war, did not reflect on itself after the war. And its structural constitution was inherited unchanged. The excessive reliance on human experimentation that remains in Japan’s medical societies today should be subjected to historical and fundamental criticism. No human being should be sacrificed for research under the fine-sounding name of “scientific progress.”

8 September 2023


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[1Jeffrey Kaye, Medium, 27 April 2021, “Department of Justice Official Releases Letter Admitting U.S. Amnesty of Japan’s Unit 731 War Criminals”.

[2The Kwantung Army was a general army of the Imperial Japanese Army from until 1945.

[3Justin McCurry, The Guardian, 27 Nov 2006, “Japanese veteran admits vivisection tests on PoWs”.

[4Unit 731: The true story behind the biological weapons crimes (Kodansha, 1995).

[5“CIA Special Collection ISHII, SHIRO_0005”. Retrieved on 6 September 2023. (https://web.archive.org/web/20200809175401/https://www.cia.gov/library/readingroom/docs/ISHII%2C%20SHIRO_0005.pdf).

[6“Chemical Weapons Program” Document from the FEDERATION OF AMERICAN SCIENTISTS retrieved on 6 September 2023 (https://nuke.fas.org/guide/japan/cw/index.html).

[7毎日新聞 (Mainichi Shimbun), 9 February 2020, “旧日本軍「731部隊」の引き揚げ経路判明 政府作成の新資料見つかる (New documents created by the Japanese government found: the salvage route of the Imperial Japanese Army’s Unit 731 identified)”.

[8Green Cross Corporation subsequently engaged in a series of corporate mergers and name changes. The company name was changed to the Mitsubishi Pharma Corporation (2001) and the Mitsubishi Tanabe Pharma Corporation (2007). Furthermore, production of blood products was taken over from the Mitsubishi Tanabe Pharma Corporation and to the Japan Blood Products Organization. The HIV contaminated blood scandal occurred in the early 1980s. And in the early 2000s, the former Green Cross Corporation was prosecuted in several drug lawsuits including hepatitis C lawsuits.

[9Walt Bogdanich and Eric Koli, New York Times, 22 May 2003, “2 Paths of Bayer Drug in 80’s: Riskier One Steered Overseas”.

[10Andrew Pollack, New York Times, 15 March 1996, “Japanese Suits on H.I.V.-Tainted Blood Settled”.