Mou then left the Shaw Brothers to become the first director from Taiwan to work in the mainland . While working on a children ’s kung fu film called '' Young Heroes '' , Mou began to hear stories about war atrocities committed by the Japanese Imperial Army during World War II . One account , of how the Japanese military had performed every manner of horrific experiment on Chinese POWs and civilians while stationed at Unit 731 in Manchuria , particularly grabbed Mou . Thus , he decided to make a film about it . Originally , he wanted to make a documentary , but he then realized that the Japanese army had destroyed or classified most of the photographs and films so he set about making a staged recreation instead . The film that resulted , a collaboration between Hong Kong and the mainland , would be the horror film '' Men Behind the Sun '' . After co-directing the hardcore pornographic film '' Trilogy of Lust '' with Julie Lee Wa-Yuet , Mou set about making a sequel to '' Men Behind the Sun '' , this time visiting the 1937 Nanjing Massacre ( or Rape of Nanking ) called '' Black Sun : The Nanking Massacre '' although this has yet to be released
Unit 731
Unit 731
Mou Tun-fei