1962, Toho purchased a script from an independent producer from America named John Beck called King Kong vs. Prometheus. Beck had stolen the story treatment (which was originally called King Kong Meets Frankenstein) from Willis O'Brien and had George Worthing Yates flesh it out into a screenplay. Toho wanted to have King Kong fight their own monster Godzilla instead of the giant Frankenstein monster in the original story and, after working out a deal with Beck as well as RKO, the copyright holder of King Kong at the time, produced King Kong vs. Godzilla. In 1964, Henry Saperstein approached Toho to co-produce Frankenstein vs. Godzilla with his company United Productions of America. The story would pit Godzilla against a giant Frankenstein Monster. Takeshi Kimura was hired to write the screenplay with Jerry Sohl and Reuben Bercovitch writing the story and synopsis for the film. The story dealt with the heart of the original Frankenstein monster becoming irradiated and growing into a giant Frankenstein Monster. Afraid the giant would start eating people, Godzilla would be awakened from slumber in the Kurile Trench by the JSDF and goaded into a fight with the Monster in hopes of destroying him. The story would end with natural disasters defeating the monsters as Godzilla disappears into a raging river flow, and the giant Frankenstein Monster disappears into magma caused by an erupting volcano. Toho was not fond of the logistics of the story, so the idea was dropped. When the Godzilla series would resume later that year, Mothra was brought in as Godzilla's next opponent for the film Mothra vs. Godzilla instead. In 1965, Toho and UPA would revive the project into this film. A new dinosaurian opponent named Baragon was created to replace Godzilla as Frankenstein's opponent and the script was slightly altered. Most of the concepts from the original story treatment were retained in this version, such as the irradiated heart of the Monster, the Monster's relentless pursuit of food and a natural disaster defeating the Monster during the climax. In addition, most of the characters from the original story, such as research scientist Dr. Bowen (played by Nick Adams), would be retained. In the American version, Jerry Sohl would get credit for a synopsis and executive producer Reuben Bercovitch would get credit for the story. Koji Furuhata earned the role of Frankenstein through an open audition. Furuhata wore green contact lenses to