
Dreaded Megalon from the undersea kingdom! A miraculous deathblow from the wound-ridden Godzilla!
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.
Kotaro Tomita
Lead Seatopian Agent
Ulf Otsuki
Seatopian Agent
Sakyo Mikami
Truck Driver's Assistant
Fumiyo Ikeda
Man from Unit 1

Robert Dunham
Emperor Antonio of Seatopia
Gentaro Nakajima
Truck Driver
Ralph Jesser
Antonio's Aide (Radio Operator in White)
Shinji Takagi
Godzilla