New documents shed light on secret wartime germ units

Asahi Shimbun

15-05-2025

One of the declassified rosters of the wartime Unit 1644 of the Imperial Japanese Army (Ryota Goto)
Previously classified personnel rosters of lesser-known wartime bacteriological units deployed in China, hidden since the end of World War II, have been released, which will help researchers better understand the nation's germ warfare effort.
The National Archives of Japan made public the rosters from 1945, which detail the names, addresses and prior affiliations of members of Unit 1644, based in Nanjing, and Unit 8604, based in Guangzhou.
These units are believed to have conducted human experimentation similar to the infamous Unit 731 of the Imperial Japanese Army during the war.
The newly released lists of Unit 1644 include names that also appear in Unit 731 records, according to Katsuo Nishiyama, a professor emeritus at Shiga University of Medical Science, who has studied Japan's wartime medical and biological programs.
'This confirms cooperation between these units,' Nishiyama said. 'It's a crucial piece of evidence that could shed light on a coordinated network of germ warfare divisions within the Japanese military.'
He hopes additional testimonies and documents will surface in the wake of this disclosure.
Both Unit 1644 and Unit 8604 were part of the Imperial Japanese Army's epidemic prevention and water purification departments and are also believed to have been involved in the development of biological weapons.
They likely operated under similar mandates to Unit 731, which was stationed in northeast China and is widely known for its brutal biological warfare experiments on Chinese prisoners of war and other victims.
The lack of surviving witnesses and documentation has made studying the activities and research of Unit 1644 particularly difficult.
One of the few references to the unit came from the late Shigeo Ban, a former member of the top-secret Noborito Laboratory, which conducted research on secret weapons and intelligence operations for the military.
In his memoir, Ban recalled a 1941 trip to Nanjing during which he witnessed a military doctor from Unit 1644 conducting live human experiments on Chinese prisoners of war.