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.

