Based on the 1964 story by master sci-fi author Sakyô Komatsu (originally published in "Manga Sunday"), Toho Company, Ltd. bought the film rights, and the resulting film was originally slated to be produced/released in 1966. The film would've starred Tatsuya Mihashi, Makoto Satô, Mie Hama, and Akiko Wakabayashi. However, the project was shelved when Wakabayashi didn't renew her contract from Toho. The same key staff (particularly director Jun Fukuda and screenwriter Ei Ogawa) would've made the film, only the special effects would've been directed by Eiji Tsuburaya.