The War of the Gargantuas

In "The War of the Gargantuas", a humanoid sea beast named Gaira, spawned from Frankenstein's monster cells, attacks Tokyo, prompting the Japanese military to intervene. Meanwhile, its Gargantua brother Sanda descends from the mountains to defend his kin, leading to a battle between good and evil that leaves brothers divided and a city in ruins. Kenji Sahara stars as Dr. Yuzo Mamiya.