Japan's Unit 731: 14,000 Killed, Crimes Unpunished

The Imperial Japanese Army's special biological and chemical warfare unit, known as Unit 731, killed approximately 14,000 people during World War II, including around 3,000 in the experiments themselves, according to a comprehensive report released on August 13, 2026. Scientists estimate that an additional 250,000 to 500,000 civilians from surrounding villages were killed through deliberate contamination of water, food, and agricultural land.

The unit's headquarters was located in the far north of Manchuria, in what is now the city of Harbin in northeastern China, which was then a Japanese puppet state. The complex consisted of 150 buildings equipped with laboratories, operating rooms, barracks, and cremation facilities, where evidence was destroyed and bodies burned at the end of the war. The victims were mostly Chinese civilians, but also Korean, Russian, British, and American prisoners of war, and the headquarters was initially disguised as a sawmill and later as a water purification plant.

Victims Called 'Logs'

The unit's doctors did not consider their victims human, referring to them as 'maruta,' or logs. In an effort to develop chemical and biological weapons, they conducted vivisection, dissecting living people without anesthesia, including pregnant women. Prisoners were infected with plague, typhus, and cholera, frozen while their hearts were still beating, and some were used as live targets for flamethrowers and mortars.

According to the report's data, the unit produced 300 kilograms of plague bacteria, 500 kilograms of anthrax, and nearly a ton of dysentery and cholera bacteria monthly-enough to wipe out all of humanity multiple times. Children were given chocolates laced with anthrax and biscuits infected with plague, while older prisoners were fed dumplings containing typhus. Men were infected with syphilis and forced to rape other prisoners to study disease transmission.

Testimony of a 95-Year-Old Veteran

Hideo Shimizu, now 95 years old, was only 14 when he was recruited as a cadet in Harbin in March 1945. In July of that year, he was taken to a sample room within the auditorium, where he saw glass jars containing severed human limbs preserved in formalin, including the corpse of a pregnant woman with her fetus.

There were those who had been cut vertically in half, so you could see their organs. There were children; ten or twenty of them, maybe more. I was stunned. I thought: 'How could they do this to a small child?'

Shimizu told the Japanese newspaper Asahi Shimbun how, three days after the atomic bomb was dropped on Nagasaki, he was called to the camp prison to bury the burned bones of murdered prisoners. Soviet forces invaded Manchuria in August 1945, and Shimizu and other unit members retreated back to Japan. Soldiers and technicians were even given cyanide and ordered to take their own lives rather than be captured.

After the war, he returned to Japan, and in 2015, 70 years after the war's end, images of his grandchildren reminded him of the victims' faces, and he decided to break his silence. Because of his public speaking about the crimes, Shimizu has been subjected to slander and abuse on Japanese social media for the past decade, where he is called a 'senile old man' and accused of lying. In an interview with Asahi Shimbun, he said: "If you say something didn't happen 100 times, it becomes as if it truly never happened. That is frightening."

Vivisection as Everyday Work

An anonymous former medical assistant in Unit 731, a farmer in his seventies, recounted in 1995 his first dissection of a living man. The report from Kurir quoted his statement:

The man knew it was over for him, so he didn't resist when they brought him into the room and tied him up. But when I picked up the scalpel, that's when he started screaming. I cut him open from chest to abdomen, and he let out a terrible scream, his face twisted in pain. He made that unimaginable sound, screaming so horribly. But then he finally stopped.

An imperial army general who came to inspect the unit wrote in his memoirs: "It was said to be for national defense, but the experiments were carried out with terrible brutality, and the dead were burned in high-voltage furnaces, leaving no trace."

Immunity Instead of Justice

The commander of Unit 731, Lieutenant General Shiro Ishii, ordered the demolition of the Harbin headquarters to destroy evidence at the end of the war. American authorities secretly granted him and other officers immunity in exchange for access to their research, meaning they all escaped prosecution. Ishii was hired by the U.S. government to lecture American officers at Fort Detrick on the use of biological weapons.

During the Korean War, he reportedly traveled to Korea to participate in U.S. military activities in biological warfare, according to a 1952 statement. Historians, however, dispute claims that the U.S. military used biological weapons. Ishii died of cancer in 1959, and other members of Unit 731 later became senior officials in the Japanese government and medical profession.

Decades of Denial and the Fight for Truth

The Japanese government has never apologized for Unit 731's actions and insists it has found no evidence of experiments on Chinese prisoners. In 1997, Professor Saburo Ienaga won a three-decade legal battle with the Ministry of Education when Japan's Supreme Court ruled that censorship of school textbooks was illegal. Ienaga wrote a textbook about the Nanjing Massacre and Unit 731, but the Ministry sought to delete or revise passages about these crimes.

In 2002, a Japanese court rejected compensation claims from 180 Chinese people who said they were victims of war crimes from the 1940s. The group sought an apology and 10 million yen (about £48,000) in damages per person. The court refused the payment but for the first time acknowledged that Japan conducted biological warfare during World War II.

Nurse Tojo Ishii, in a statement from June 2006, described how workers were forced to bury bodies at the site of a former medical school in western Tokyo before American troops arrived: "We took samples from the glass jars and threw them into a hole. I was told we would be in trouble if American soldiers asked about the samples."

In 2023, Chinese archaeologists excavated a research facility hidden beneath two meters of earth, believed to be the largest and most frequently used testing site of Unit 731. The U-shaped bunker, built in 1941 near the city of Anda in Heilongjiang Province, is a network of laboratories, dissection rooms, and holding cells.