Unit 731 (Japanese: 731部隊, Hepburn: Nana-san-ichi Butai), officially known as the Manchu Detachment 731 and also referred to as the Kamo Detachment and the Ishii Unit, was a secret research facility operated by the Imperial Japanese Army between 1936 and 1945. It was located in the Pingfang district of Harbin, in the Japanese puppet state of Manchukuo (now part of Northeast China), and maintained multiple branches across mainland China and Southeast Asia.
Unit 731 was responsible for large-scale biological and chemical warfare research, as well as lethal human experimentation. The facility was led by General Shirō Ishii and received strong support from the Japanese military. Its activities included infecting prisoners with deadly diseases, conducting vivisection, performing organ harvesting, testing hypobaric chambers, amputating limbs, and exposing victims to chemical agents and explosives. Prisoners—often referred to as "logs" by the staff—were mainly Chinese civilians, but also included Russians, Koreans, and others, including children and pregnant women. No documented survivors are known.