Though I haven't seen The Human Vapor (and since it's not on DVD, you probably haven't either), I want to now because this poster really sells the film. In fact, it oversells it. I've always loved how bombastic promotional materials were for pre-'70s films. Posters and trailers promised everything and rarely delivered. The Human Vapor is sold like a monster movie with a space element, though the titular character's as much a monster as the Invisible Man, and I'm pretty sure a gaseous mass isn't too beastly. To ensnare a wary female audience, The Human Vapor is infused with a bit of tragedy since he still "loves like a man." Basically, American distributor Brenco Pictures marketed this film with a kitchen sink approach that shouts, "Please don't realize this film is from Japan!"
That's right, The Human Vapor is the American release for Toho Studio's Gasu Ningen dai Ichigo[ガス人間第一号,, The First Gas Person], and was made by Godzilla crew Ishirō Honda, Tomoyuki Tanaka and Eiji Tsuburaya. In the film, a librarian (Yoshio Tsuchiya) undergoes an experiment that enables him to turn into vapor. He uses these new powers to commit crimes to help his dancer girlfriend (Kaoru Yachigusa) with her comeback. Character-based tragedy ensues, along with a lots of quality special effects!
The film didn't do too well in US theaters and was apparently seen by most North American viewers on television during the '70s. Oddly enough, Yoshio Tsuchiya prefers the American cut of the film over the original Japanese version because it tells the story from his character's point-of-view (and possibly because he's dubbed by James Hong).
Finally, if you're one of those Sci-Fi surf rock fans who were wondering whether or not this is where the Outer Space (via Alabama)-based band Man...Or Astro-Man? got their name, the answer is yes.