Synopsis
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.
Cast

Katsuhiko Sasaki
Inventor Goro Ibuki

Yutaka Hayashi
Hiroshi Jinkawa

Hiroyuki Kawase
Rokuro 'Roku-chan' Ibuki
Kanta Mori
Japan Special Defense Forces Chief

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
Hideto Odachi
Megalon
Tsugutoshi Komada
Jet Jaguar
Masachika Mori
Jet Jaguar

Kenpachirō Satsuma
Gigan (as Kengo Nakayama)

Gorō Naya
Emperor Atonio of Seatopia (voice)
Eisuke Nakanishi
Narrator

Haruo Nakajima
Godzilla (archive footage) (uncredited)
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