[[caption-width-right:350:The director T.F. Mou [[{{Anvilicious}} subtly presents]] the message of the film.]]

One of the most disturbing films to ever come out of Eastern Asia.

Released in 1988, ''Men Behind the Sun'' (''Hei tai yang 731'', ''The Black Sun Unit 731'' in native Hong Kong) is a film about the Imperial Japanese Army's Unit 731, which during World War II conducted medical research and biological/chemical weapon experiments on captive human subjects. The film details many of the experiments carried out by the unit, and also follows a group of recruits to the unit's Youth Corps.

''Men Behind the Sun'' is supposed to be a rather horrifyingly accurate depiction of Unit 731's activities in real life. However, the director based it on a fictional novel serialized in a Japanese Communist Party newspaper of questionable quality, to which can be traced the origins of many dubious facts regarding the Unit, as well as confusing the activities of Unit 100 with Unit 731. Whether the film is a cheap and horrific ExploitationFilm or a valid commentary on the behavior of the Imperial Japanese Army is debated. Either way, it's guaranteed to utterly ruin your day.

!!This film provides examples of:

* AdultFear: The gas chamber experiment featuring [[spoiler: a mother begging for her child not to be harmed as they're both gassed to death.]]
* BasedOnATrueStory: Most or all of the experiments depicted actually took place, as did most of the historical background.
* BodyHorror: The film features electrocutions, bloody beatings, dismemberment, rotting corpses, frozen limbs being broken off, severe frostbite, gassings, disembowelment, burning corpses, and to top it all off an autopsy on a real child's cadaver.
* CouldntFindAPen: One of the ''maruta'' scrawls a condemnation of his captors on the wall of his cell in his own blood [[spoiler:when they're all gassed to death.]]
* CruelAndUnusualDeath: The guy in the pressure chamber.
* CyanidePill: In a bottle this time, given to all the important personnel to use if they were captured.
* EvilIsHammy: Shiro Ishii, especially when he demonstrates his idea for a new bacterial bomb.
* ExploitationFilm: Unintentional, but is regarded as such my some.
* ForScience: War or not, this was the justification for many researchers.
* GasMaskMooks: Many soldiers wear these when dealing with the prisoners or hazardous materials.
* {{Gorn}}: Of all kinds, including a real child's cadaver cut open on film.
* HarmlessFreezing: Averted. One woman's arms are slowly frozen by having cold water poured over them while outside in freezing temperatures only to have them [[spoiler: soaked in warm water, allowing the skin to be pulled right off down to the bone.]]
** Another man had his arms put in a flash freeze chamber and [[spoiler: had his frozen fingers beaten off with a pipe.]]
* HazmatSuit: Worn by almost everyone while around the lab and the many hazardous materials and diseases they were working on.
* KarmaHoudini: As the film points out, Ishii and most of his men escaped judgment after the war.
* KickTheDog: Except it's not a dog, it's a cat. And it's not kicked, it's [[spoiler:eaten alive by rats.]] Also, the mute child is either kicked or [[ShootTheDog shot]], depending on one's view of the scientific value of the act.
* KillItWithFire: Unit 731's rat colony is disposed of with fire at the end. The live were actually set on fire for the scene as well.
* LeaveNoSurvivors: When [[spoiler:Japan surrenders and Unit 731 is ordered to disband they kill all the maruta in the prison.]]
* MadDoctor: All the medical professionals there due to the sheer level of atrocities they commit in the name of research.
* MadScientist: The ultimate goal of Unit 731 and Ishii was to create a version of the Bubonic Plague that could turn the tide of the war.
* MedicalHorror:
* MorallyAmbiguousDoctorate: And how.
* NoAnimalsWereHarmed: {{Played straight}} with the infamous scene of the cat being devoured by rats; it was red-dyed honey and the cat was rewarded with fish before being sent home to its owner.
** Averted with the rats themselves, [[spoiler:which were actually set on fire.]] No word either way on the gas chamber dove.
* PleaseIWillDoAnything: {{Invoked}} word-for-word by [[spoiler: a mother who was being locked in a gas chamber with her daughter.]]
* RuleOfSymbolism: The image at the top comes from a scene at the end in which someone attacks Ishii and the other 731 leaders for their crimes. The attacker is stabbed with a flag pole. This unlikely weapon is used primarily so that we can see the Japanese flag soiled with blood.
* SequelDecay: The film was followed by several sequels, none of which were anywhere near as shocking as the original.
* SlowClap: When Ishii demonstrates his low-temperature bacterial bomb,although it quickly turns into loud applause.
* StrappedToAnOperatingTable: {{Subverted}} as the child willingly got on the table because he was completely clueless to what they were going to due. Eventually he was knocked out before the surgery began so he wasn't able to resist.
* TheSpeechless: A mute child serves as an excellent dog for kicking.
* WouldHurtAChild: Several are killed brutally over the course of the film. The soldiers seem to go out of their way to do it.