Made with the approval of the Chinese Central Committee, Mou Tun Fei's 1988...er..."classic" is really nothing more than a Chinese propaganda/exploitation flick dressed up as an historical document on Japanese atrocities carried out at the Unit 731 experimental warfare research facility in the Chinese puppet state of Manchuko during WWII.
However, there absolutely nothing on offer here that is of factual substance, other than the fact that Unit 731 existed and was concerned with finding a viable way to use bacterial/chemical warfare as a means to pursue a Japanese victory in the Second World War.
As much of the first hand documentary evidence has long since disappeared, it therefore stands to reason that what really happened at Unit 731 will always remain a matter of conjecture in a lot of areas of concern. That it was a place of brutal experimentation and atrocity, is something few will disagree with, but the actual facts of Unit 731 will be found in the written word, not in this film and as such people interested in further understanding the facility and the people who were there will have to seek out the few books on the subject that exist.
Mou's film has enjoyed a lot of respect in some quarters and it's truly incredible that there are quite a few people really think that they are watching some sort of factual account, even though the frankly absurd torture on screen is indicative of a horror/exploitation angle rather than an historical document. The utter pointlessness of the "experiments" presented should have been a clue to everyone that what they were looking at was more akin to 'Ilsa: She Wolf of the SS' or 'Love Camp 7', than something of more historical worth. The notorious frostbite experiments are evidence of this. In one scene, a woman is left out in the extreme cold so her arms become badly frostbitten and then she is brought inside the facility and told to dip her arms in heated water. When she withdraws them, the "Japanese" researcher then strips the flesh from her bones leaving her with two skeletal arms. This famous and shocking scene is great for exploitation cinema lovers (of which I am one), but is absolutely useless as a document on real frostbite tests. This "experiment" in 'Men Behind the Sun' would serve absolutely no scientific purpose whatsoever. Another frostbite test has a man's arms frozen and then his fingers are smashed with a hammer, again in an utterly pointless (but highly shocking) "experiment" scene. Other pointlessness includes a live vivisection on a young boy and throwing a cat to starving rats. The former has been touted by the director as a real vivisection (which clearly it's not & I believe Mou has dropped that particular hype) and the latter has been said to have been a real cat attacked and eaten by real rats. While the animals are real, there has been some dispute to whether the scene has been faked. Either way, it actually remains the most disturbing scene in the movie. But again, while this serves the purpose of a horror/gore movie, it does nothing else. In fact, such silliness subtracts from the film's supposed stated goal, as a sober document on Unit 731.
By the way, the rats themselves were later really set on fire for one of the movies final scenes in a truly appalling and un-necessarily cruel stunt.
The opening tag line of the film. "Friendship is friendship. History is history." suggests a more serious execution of a serious matter. But, the end product fails miserably in that respect. Even the actual nature of the film (exploitation cinema) fails ultimately, because the film is just not gritty or gory enough. There are also long, long periods of boredom sprinkled throughout and the characters never once match up to real people. The overdubbed (Asian) soundtrack is bothersome as well, mainly due to its cheap nature and the print quality is rubbish.
'Men Behind the Sun' certainly is an interesting film in parts, but not for the reasons espoused by its makers. It does have some inventive atrocity (for those who wish to seek out such material) and well done special effects. But, as a factual document, it's worthless.