Detachment 731 , the 731 Regiment , Manshu Detachment 731 , The Kamo Detachment , or the Ishii Company , was a covert biological and chemical warfare research and development unit of the Imperial Japanese Army that undertook lethal human experimentation during the Second Sino-Japanese War ( 1937 – 1945 ) of World War II . It was responsible for some of the most notorious war crimes carried out by Imperial Japan . Unit 731 was based at the Pingfang district of Harbin , the largest city in the Japanese puppet state of Manchukuo ( now Northeast China )
war crimes carried out by Imperial Japan
Japanese war crimes
Unit 731