The Human Vapor

1960 film by Ishirō Honda

is a 1960 Japanese science fiction film directed by Ishirō Honda, with special effects by Eiji Tsuburaya. Produced and distributed by Toho Co., Ltd., it is the third and final film in the Transforming Human Series. In the film, a scientific experiment goes awry and turns its subject into an unstoppable gaseous mutant who takes advantage of his abilities and commits ruthless crimes.

While investigating a mysterious bank robber, Detective Okamoto encounters dancer Fujichiyo Kasuga and her servant, Jiya. Okamoto's girlfriend, newspaper reporter Kyoko Kono, insists on helping him, despite him not taking her seriously. Shortly thereafter, another bank is robbed, with the culprit mysteriously evading all security measures, surviving gunfire from a police officer, and killing the officer and an employee before vanishing. Kyoko informs Okamoto that Fujichiyo is from a wealthy and respected family, but has not performed in some time. He also learns from his superior Tabata that the bank victims died from asphyxiation. Okamoto and Kyoko discover that Fujichiyo is planning to perform again, but is reticent about the details. They follow her to a library, where the librarian Mizuno tells them that she has been studying ancient songs and engravings. Fujichiyo also approaches a respected chamber music tutor named Osaki and offers him to perform. Okamoto reports these findings and his suspicion of her possible sponsor to Tabata, who recommends continuing to investigate Fujichiyo's dealings. A suspect is arrested after making a call to Kyoko's newspaper announcing the date and time of the next robbery, but Okamoto and Kyoko feel that his story does not add up. Their suspicions of Fujichiyo appear confirmed when she attempts to pay for a theater space with stolen money. She is arrested and questioned, but refuses to say where the money came from. Sometime later, Mizuno surrenders himself to the police and offers to show them how he committed the robberies. He is brought to the second bank he robbed, where he demonstrates his ability to turn himself into a gaseous form that allows him to evade gunfire, pass through vault bars, and asphyxiate another cop. Before he escapes through an overhead window, he demands Fujichiyo's release, but she still refuses to cooperate and is kept in police custody. Mizuno attempts a rescue, but she refuses to leave and be seen as a criminal herself. Mizuno instead releases the other prisoners, causing a clash with police. Kyoko convinces her newspaper to print an invitation to Mizuno, who arrives at the designated time and place. He explains that a scientist named Dr. Sano experimented on him and caused his transformation. Mizuno then killed Dr. Sano in a rage, but is now grateful for his powers and the chance to help his love Fujichiyo dance again. The police arrive and attempt to subdue Mizuno, but he escapes once again. The police are soon forced to release Fujichiyo, as she cannot be charged. She proceeds with her performance plans despite the musicians' refusal to attend out of fear. Mizuno visits her and declares his love, saying he would do anything for her. Scientist Dr. Tamiya meets with Okamoto and Tabata to devise a plan to destroy Mizuno using explosive gas. Kyoko pleads with Fujichiyo to cancel the performance, but she refuses, feeling it is her destiny and expressing love for Mizuno. On the night of the recital, as media and emergency crews observe the theater, a number of onlookers enter, demanding to see the "Human Vapor". Mizuno stands before them, announces that he is the Human Vapor, and transforms, scaring the crowd away. Fujichiyo and Jiya insist on continuing, and despite Kyoko's pleas, the switch is thrown to detonate the theater, but the circuit board has been sabotaged and the plan appears to be a failure. As the performance ends and Mizuno embraces Fujichiyo, she covertly pulls out a cigarette lighter and strikes it, destroying herself, Jiya (who chose to stay with her to the end), the theater, and Mizuno, who returns to solid form in death.

The third in Toho’s “Transforming Human” series, The Human Vapor, was almost directed by Jun Fukuda before Ishiro Honda became available. Early versions of the script are similar to the finished film except for one scene Honda insisted be cut, Mizuno was to have murdered the wife and child of a policeman. Storyboards also show a much more dramatic version of the scene where Mizuno escapes the police from a high rise building. In the storyboards, Mizuno dramatically jumps through the glass. We cut to an exterior shot of Mizuno’s clothes flapping in the air as he dissolves while the police are shooting at him. The script, by Takeshi Kimura, had been languishing at Toho since 1958 before production began. In addition, original drafts of the film were simply titled Toho's Third Mutant Movie. By the time it was released, though, it had been beaten to the market by other films in the genre such as The Secret of the Telegian (1960) earlier that year. For reference, the earlier two "mutant" films being referenced were The Invisible Avenger (1954) and H Man (1958).

Producer Tomoyuki Tanaka asked actor Tadao Nakamura, who was Sudo the telegraphed man in The Secret of the Telegian (1960) to play the Mizuno the vapor man for this film but declined. Kunio Miyaguchi’s music for this film would later be reused in the Tsuburaya Productions TV shows Ultra Q (1966) and Ultraman (1966 67).

A rubber balloon mannequin of Tsuchiya was made and was used to simulate the Gas Man’s transformation. Air was inflated into the balloon and deflated while filmed at high speed. Small grains of dry ice were placed inside and exposed to lukewarm water, with the balloon allowing the resultant smoke cloud to retain a human shape.

The film was distributed in Japan by Toho on December 11, 1960. It was later released in the United States as The Human Vapor by Brenco Pictures with an English language dub May 20, 1964. The film was released as a double feature with Gorath, and was edited down to 79 minutes.

In a contemporary review, "Whit." of Variety declared the film plot superior to its companion double feature Gorath and that its special effects by Eiji Tsuburaya were "expert", while the acting was "competent". The review concluded that the English language dub they watched was "far from gratifying" and that when the lips did not match the English dialogue, it "decreased realism".

Due to its box office success in the United States and Europe, an American film company proposed that Toho produce a sequel to the film. In February 1963, Shinichi Sekizawa wrote the first draft for the sequel, entitled Frankenstein vs. the Gas Man (フランケンシュタイン対ガス人間). According to producer Tomoyuki Tanaka the film was to depict "the gas man looking for Dr. Frankenstein in order to revive Fujichiyo". A depiction of Frankenstein's monster was later used in Frankenstein vs. Baragon (1965). In 2024, a Netflix series adaptation of the film was announced. Co produced by Toho and Wow Point, Yeon Sang ho would serve as showrunner and writer for the series, with Yu Aoi and Shun Oguri in starring roles.