The Human Vapor, known in Japan as Gas Human No. 1 (ガス人間第一号, Gasu Ningen dai Ichi-gō), is a tokusatsu film produced and released by Toho Studios in 1960. The film was made by Toho's legendary Godzilla directing/special effects/producing team of Ishirō Honda, Eiji Tsuburaya, and Tomoyuki Tanaka.
The film was recut by Brenco Pictures in 1964, changing the format from that of a mystery to a narrative being told largely in flashback from Mizuno's point of view. Even though this version is dubbed, Tsuchiya has stated that he prefers this cut of the film, which he considers to feature his finest performance.
A sequel to this film was planned called Frankenstein vs. the Human Vapor in which the Human Vapor survives the climax and goes to find a doctor who brought Frankenstein's monster to back to life, in hopes of finding a way to bring back his girlfriend who didn't survive the climax leading to a battle between the two. This was dropped in favor of Frankenstein Conquers the World (the 1957 film Tomei-Ningen To Hae-Otoko or Invisible Man vs. Fly Man is available in North America under the title Vapor Man Meets the Human Fly, but it is not related).
The film tells the story of Mizuno (Yoshio Tsuchiya), a librarian who has been given the ability to become vapor after a scientist (Fuyuki Murakami) performs an experiment on him. Mizuno uses this power to engage in criminal activities, robbing banks to give the money to his love interest, the dancer Fujichiyo (Kaoru Yachigusa). Police Lieutenant Kenji Okamoto (Tatsuya Mihashi) and his reporter girlfriend Kyoko (Keiko Sata) work together to solve the criminal case and attempt to bring things to a peaceful conclusion.