Katsuhiko Sasaki
Inventor Goro Ibuki
Acting
Yutaka Hayashi
Hiroshi Jinkawa
Acting
Hiroyuki Kawase
Rokuro 'Roku-chan' Ibuki
Acting
Kanta Mori
Japan Special Defense Forces Chief
Acting
Kotaro Tomita
Lead Seatopian Agent
Acting
Ulf Otsuki
Seatopian Agent
Acting
Sakyo Mikami
Truck Driver's Assistant
Acting
Fumiyo Ikeda
Man from Unit 1
Acting
Robert Dunham
Emperor Antonio of Seatopia
Acting
Gentaro Nakajima
Truck Driver
Writing
Ralph Jesser
Antonio's Aide (Radio Operator in White)
Acting
Shinji Takagi
Godzilla
Acting
Hideto Odachi
Megalon
Acting
Tsugutoshi Komada
Jet Jaguar
Acting
Masachika Mori
Jet Jaguar
Acting
Kenpachirō Satsuma
Gigan (as Kengo Nakayama)
Acting
Gorō Naya
Emperor Atonio of Seatopia (voice)
Acting
Eisuke Nakanishi
Narrator
Acting
Haruo Nakajima
Godzilla (archive footage) (uncredited)
Acting