'The First Gas Man') is a 1960 Japanese science fiction film directed by Ishirō Honda, with special effects by Eiji Tsuburaya.

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 robbery, Detective Okamoto encounters dancer Fujichiyo Kasuga and her servant, Jiya.

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 two more people.

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".

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.

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.

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.

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".

[5] 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".

[6] In February 1963, Shinichi Sekizawa wrote the first draft for the sequel,[7] entitled Frankenstein vs. the Gas Man (フランケンシュタイン対ガス人間, Furankenshutain tai Gasu Ningen).

Co-produced by Toho Studios and Wow Point, Yeon Sang-ho would serve as showrunner and writer for the series, with Yu Aoi and Shun Oguri in starring roles.