Men Behind the Sun (Chinese: ???731 / ???731; pinyin: h?i tài yáng 731) is a 1987 Hong Kong film directed by Mou Tun Fei.
The film is a graphic depiction of the war atrocities committed by the Japanese at Unit 731, the secret biological weapons experimentation unit of the Imperial Japanese Army during World War II. The film details the various cruel medical experiments Unit 731 inflicted upon the Chinese and Soviet prisoners at the tail-end of the war.
The movie opens with the passage "Friendship is friendship; history is history," implying that the film's intent is not to demonize the modern Japanese, but to simply portray a factual part of Imperial Japan's history in China.
The film follows a group of Japanese boys who have been conscripted into the Youth Corps. They are assigned to the Kwangtung Army, and are brought to one of the facilities serving Unit 731, which is headed by Shiro Ishii. Soon, they are introduced to the experiments going on at the facility, for which they feel revulsion. The purpose of the experiments is to find a highly contagious strain of bubonic plague, to be used as a last-ditch weapon against the Chinese population.
Meanwhile, the young soldiers befriend a local mute Chinese boy who they play games of catch with. One day, the commanding officers ask the boys to bring the Chinese child to the facility. Naively, they follow orders believing that no real harm will come to the boy. However, the senior medical staff places the boy in surgery for the purpose of harvesting his organs for research. When the young soldiers realize what has happened, they stage a minor uprising by grouping up and physically beating their commanding officer.
As the war goes on, the situation becomes increasingly desperate for the Japanese, and therefore Unit 731. In one of their last experiments, they tie a number of Chinese prisoners to crucifixes, intending for them to be used as targets for a prototype ceramic bomb containing infectious fleas. However, they are not able to contact their airfield due to a retreat. The Chinese prisoners break free from the crucifixes, and attempt to escape. However, the Japanese troops hunt them down, and nearly all of them are run over or shot. Several Japanese are also killed or injured....