The War of the Gargantuas

Released in Japan in 1966 as "Frankenstein's Monsters: Sanda versus Gaira" and a semi-sequel to Frankenstein Conquers The World. It introduces two giant, hairy humanoids called Gargantuas, which spawned from the discarded cells of Frankenstein's Monster from the previous film and are described as brothers. The Green Gargantua is violent and savage, preying upon human beings as he lives in sea water, he is given the name Gaira for "stranger." The Brown Gargantua had been raised in captivity, and is docile and gentle because he resides in the Japan Alps, he is called Sanda for "mountain". The film follows the investigation and military engagements of these creatures until their climatic confrontation in Tokyo.