is a 1958 Japanese science fiction thriller film directed by Ishirà  Honda, written by Takeshi Kimura with special effects by Eiji Tsuburaya. It stars Kenji Sahara and Akihiko Hirata. It is the first film in Toho's Transforming Human Series, followed by The Secret of the Telegian and The Human Vapor (both 1960).
On a rainy night, two suspicious men emerge from the sewers in Tokyo. Suddenly, one of the men begins to moan in pain, fires a pistol, and then vanishes without a trace, leaving behind his clothes and a large quantity of drugs.
Detective Tominaga of the Tokyo Metropolitan Police traces the missing manâÂÂs identity to Misaki, a known gang member, and deduces that the men may have been planning a drug smuggling operation. Tominaga interrogates Chikako Arai, a singer at the cabaret Homura and MisakiâÂÂs mistress, who had been approached by the mysterious men. However, the manâÂÂs true identity turns out not to be a gang associate but TominagaâÂÂs friend, Masada, an assistant professor of biochemistry at Joto University.
Masada theorizes that the disappeared Misaki may have been exposed to large amounts of radioactive material and transformed into a âÂÂLiquid Men.â He presents evidence including eyewitness accounts of sailors from the Ryujin-Maru II, who had been irradiated during a South Pacific hydrogen bomb test and allegedly became liquid Men, experimental results showing frogs liquefying under intense radiation, and a life preserver from the Ryujin-Maru II found near Eitai Bridge. The police dismiss these claims as insufficient evidence. Meanwhile, strange incidents occur around Chikako, including gang members who attempt to attack her mysteriously disappearing.
The investigation hits a dead end, but testimony from Chikako points to HomuraâÂÂs waiter, Shimazaki, as possibly connected to the incidents. The police mobilize a raid on the cabaret in Tsukiji. At the same time, a Liquid Human emerges from the Sumida River and liquefies the cabaretâÂÂs dancers, officers, and Shimazaki. Recognizing the gravity of the situation, the investigators take Masada and his mentor, Dr. Maki, implement a plan to pour gasoline into the sewers near the Sumida River and set it ablaze, successfully exterminating the Liquid Men.
During these events, Masada and Chikako develop a romantic relationship. However, Uchida, a gang member who had partnered with Misaki, abducts Chikako to recover the drugs hidden in the sewers. Uchida is killed by a Liquid Man, and Chikako is endangered by the dual threats of the Liquid Men and the spreading fire. Masada and TominagaâÂÂs search team dive into the sewers and rescue her safely.
The fire along the Sumida River ultimately destroys all remaining Liquid Men. Nevertheless, Dr. Maki warns that if Earth were ever covered in deadly radioactive fallout and humanity were wiped out, the Liquid Men might be the next dominant life form on the planet.
The H-Man was distributed theatrically in Japan by Toho on June 24, 1958.
The film was released theatrically in the United States on June 23, 1959 by Columbia Pictures with an English-language dub and 79-minute running time. It played on a double feature with The Woman Eater (1959).
The original Japanese version of the film focuses a similar amount of time on the drug-running criminals as activities of the H-Men. This was cut in the English dubbed film.
Columbia released The H-Man on VHS. The film was released on DVD in 2009 in the United States.
From contemporary reviews, A New York Herald Tribune film critic at the time called it, "A good-natured poke at atom-bomb tests[.] The picture is plainly making a case against the use of nuclear bombs. At the same time, there is a great deal of lively entertainment in the story involving police, dope smugglers, scientists and some very pretty Japanese girls." The Daily Variety described the film as "well made" "seemingly more thoughtful" than The Mysterians and Gigantis. The review noted Takeshi Kumra's screenplay as "effective" and Honda's direction as taking "full advantage of the story [which is a] technically excellent production." The Monthly Film Bulletin noted the film had "all the usual faults and virtues of Japanese SF-cum-horror fiction[.] But for special effects, trick photography and spectacular staging, the Japanese again beat their Hollywood counterparts at their own game: The fantasy element of vanishing bodies and mobile liquid is brilliantly done."