Furankenshutain no Kaijū: Sanda tai Gaira

The name of this movie is Furankenshutain no Kaijū: Sanda tai Gaira released in 1966-07-29 and it's main theme is 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..