Inventor Goro Ibuki creates a humanoid robot named Jet Jaguar. It is soon seized by an undersea race of people called the Seatopians. Using Jet Jaguar as a guide, the Seatopians send Megalon as vengeance for the nuclear tests that have devastated their society.
Katsuhiko Sasaki
Hiroyuki Kawase
Yutaka Hayashi
Robert Dunham
Kotaro Tomita
Ulf Otsuki
Gentaro Nakajima
Sakyo Mikami
Fumiyo Ikeda
Kanta Mori
Rolf Jessup
Eisuke Nakanishi
Shinji Takagi
Hideto Odachi
Tsugutoshi Komada
Kenpachirō Satsuma