A womanizing reporter for a sleazy tabloid magazine impersonates his hen-pecked neighbor in order to get an expose on renowned psychologist Helen Gurley Brown.

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.