Tōru Ibuki

Four men searching for one's brother are shipwrecked on Letchi Island, where a terrorist organization developing nuclear weapons have enslaved the natives of Infant Island and command monstrous crustacean named Ebirah.

The evil Dr. Who captures King Kong to dig for Element X when his robot duplicate, Mechani-Kong, is unable to do the job, but Kong soon escapes and battles his doppelganger.