Gaira, a humanoid sea beast spawned from the discarded cells of Frankenstein's monster, attacks the shores of Tokyo. While the Japanese military prepares to take action, Gaira's Gargantua brother, Sanda, descends from the mountains to defend his kin. A battle between good and evil ensues, leaving brothers divided and a city in ruins.
as Dr. Yuzo Mamiya
as Akemi Togawa
as Dr. Paul Stewart
as General Hashimoto
as Singer
as Officer Hirai
as Professor Kita
as Chief Izumida
as Lt. Col. Kazama
as Saburo Kameda
as General's Aide
as Soldier
as Defiant Reporter
as Skeptical Reporter
as Fisherman #1
as Fisherman #2
as Official
as Dr. Paul Stewart (voice)
as Gaira
as Sanda
as Adolescent Sanda
as Adolescent Sanda (voice)
as (uncredited)