Unit 516 ( 第五一六部隊 ) was a top secret Japanese chemical weapons facility , operated by the Kempeitai , in Qiqihar , Japanese-occupied northeast China . The name Unit 516 was a code name ( Tsūshōgō ) of the Unit . It was officially called the Kwantung Army Chemical Weapons Section and operated underneath Unit 731
Unit 731
Unit 731
Unit 516