Minoru Chiaki
Kobayashi (as Mindru Chiaki)
Takashi Shimura
Dr. Yamane
Masao Shimizu
Dr. Tadokoro
Seijirô Onda
Commander (as Serjiro Onda)
Mayuri Mokushô
Radio Operator
Yukio Kasama
Father (as Yokio Kasama)
Minosuke Yamada
Chief of Civil Defense (uncredited)
Ren Yamamoto
Ikeda (uncredited)
Shin Ōtomo
Convict Leader (uncredited)
Senkichi Ōmura
Convict (uncredited)
Haruo Nakajima
Gigantis (uncredited)
Katsumi Tezuka
Angurus (uncredited)
Shōichi Hirose
Convict (uncredited)
Keye Luke
Tsukioka / Policeman (voice) (uncredited)
Aya Oyama
Hidemi (voice) (uncredited)
Marvin Miller
Kobayashi / Dr. Yamane / Narrator (voice) (uncredited)
Paul Frees
Commander / Father / Convict (voice) (uncredited)
George Takei
Ikeda / Osaka SDF Dispatcher (voice) (uncredited)
Jane Chang
Radio Operator (voice) (uncredited)
James Yagi
Osaka SDF Captain (voice) (uncredited)
