Astronauts Glenn and Fuji investigate Planet X and encounter mysterious aliens known as the Xiliens, who ask Earth's people to help save their world from "Monster Zero". In exchange for borrowing Godzilla and Rodan, the Xiliens offer a cure for cancer. As Glenn investigates, he develops a romance with Miss Namikawa and uncovers the Xilien's true intentions.
Akira Takarada
Astronaut Kazuo Fuji
Nick Adams
Astronaut F. Glenn
Kumi Mizuno
Miss Namikawa
Keiko Sawai
Haruno Fuji
Jun Tazaki
Dr. Sakurai
Yoshio Tsuchiya
Controller of Planet X
Akira Kubo
Tetsuo Torii
Takamaru Sasaki
Chairman of Earth Committee
