Men Behind the Sun (1988)
Original title: 黑太陽731
Men Behind the Sun is a 1988 Chinese-language war movie directed by Mou Tun-Fei, with a running time of 1h 45m. It stars Gang Wang, Wang Runshen and Hsu Gou.
Japanese troops round up Chinese and Russian prisoners of war and take them to unit 731, where they're horribly tortured and experimented on to test new biological weapons.