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.

The Battle of Midway was a major naval battle in the Pacific Theater of World War II that took place 4–7 June 1942, six months after the Empire of Japan's attack on Pearl Harbor and one month after the Battle of the Coral Sea.