Any self-made film historian can tell you that during the American occupation of Japan after WWII, the Supreme Commander for the Allied Powers (aka Douglas MacArthur) pulled the plug on Japan’s jidai-geki (period films) for fear they would promote feudal and nationalist spirit. 
Unfortunately, this ban also slapped the cuffs on Japan’s bountiful horror movies, which for the most part also showcased Edo-era topknots and kimonos.
In lieu of old-school neko onna and Tokaido-road ghost stories came new-breed modern thrillers that featured glamorous and tawdry nightclub acts, men who challenged science and became monsters, all shot with touches of German expressionism filtered through American film noir.
During the waning days of SCAP’s influence, Daiei Studios developed a cozy line of such shockers. On 1949’s calendar alone there was Hakuhatsuki (White Haired Demon), a Dracula-like film designed as a vehicle for actor Kanjuro Arashi (a former period movie superstar who thanks to SCAP was then facing unemployment); Niji-otoko (Rainbow Man), in which a psychopath kills folks after dosing them with mescaline; and Toumei ningen arawaru (The Invisible Man Appears), with effects by Eiji Tsuburaya, Godzilla’s main man who routinely provided SFX for the Daiei nasties. 
Daiei’s forward-thinking formula was a low-budget concoction of crime, women’s kneecaps, and monster-on-the-loose mayhem. Ex-carnival showman Mitsugu Okura would be inspired to produce similar films under his Shin Toho banner in the late Fifties. And Toho themselves would create more upscale color ‘n’ scope versions with their “mutant” series, a la 1958’s The H-Man and 1960’s The Human Vapor (both directed by Ishiro Honda).
This little history lesson takes us right into Tetsu no Tsume (Claws of Iron), Daiei’s and 1951’s answer to Dr. Jekyll and Mr. Hyde, Murders in the Rue Morgue, and King Kong, with a lot of daring cabaret numbers strewn in between for that “hubba hubba” effect. 
A series of gruesome murders leads the police to the swanky Melody nightclub and to vampish “entertainer” Yukie (Maria Sono). The cold stiffs are culled from among her many lovers, so the chief suspect becomes her ex-husband Tashiro (Joji Oka, who also wrote the film’s dubious scenario under a pseudonym). Suspicions prove correct when it is discovered that during a stint as a solider in the South Pacific, Tashiro was bitten by a wild gorilla (a man in an ape suit, straight out of a Republic serial). Ever since then, whenever he’s on the receiving end of “strong stimulation,” he transforms into a toothy, flat-nosed gorilla man, which is bad news for his new image as a Jesus-loving man of the cloth.
After turning into a misshapen mockery of man at the nightclub, (the very home of “strong stimulation”), he grabs a showgirl (a dummy, actually). Climbing quickly to the rooftops, with a requisite angry mob shouting below, our truly unlucky ape man falls to his death. For a coda, we are provided the comforting image of his dead double-exposed spirit walking across the Ginza skyline to a church for a proper Christian service.
Directed by Nobuo Adachi, who also helmed The Invisible Man Appears, Claws of Iron has the Balls of Iron to suggest that people who survived fighting in the war are actually monsters. Also, you’ve got to love that jackhammer nightclub-church dialectic with many a scene cutting directly from one to the other. And just when things start getting too plotcentric, the narrative all but stops so a scientist can make a woman’s clothes disappear with the aid of a electrical machine.
All of which proves that there was more going on at Daiei in 1951 than Rashomon, which won accolades at the Venice Film Festival and the Academy Awards that same year. Hallelujah!