When a giant stone statue on Wester Island is disturbed, the legendary monster Jiger appears and heads for Japan. Gamera tries to stop this new rival, only to be injured when Jiger lays eggs inside of him. As two boys in a submarine go on a dangerous quest inside of Gamera's body to save him, Jiger threatens the Expo '70 world's fair in Osaka.
Tsutomu Takakuwa
as Hiroshi Kitayama
Kelly Varis
as Tommy Williams
Katherine Murphy
as Susan Williams
Ryô Hayami
as Keisuke Sawada
Franz Gruber
as Dr. Williams
Junko Yashiro
as Miko Kitayama
Kon Omura
as Ryosaku Kitayama
Umenosuke Izumi
as Gamera
Chico Lourant
as African Ambassador
Shō Natsuki
as Dr. Suzuki