This movie was released in the U.S. by American International Television, who renamed it Return of the Giant Monsters.
It all starts when a series of volcanos go off, attracting Gamera, who enters one of them. This reveals a new monster, Gyaos, named for the sounds he makes. It looks like a giant bat and has wind powers, which he uses to decimate the Japanese Self-Defense Force.
Gyaos is a formidable opponent, as he has beams that cancel out Gamera’s fire breath. He’s also willing to bite off his own toes to save himself from Gamera’s fierce fangs. It takes Gamera dragging Gyaos into one of those volcanos to kill him.
This film presents a world where money is more important than the lives and needs of the poor, even in the face of a monster ready to kill all of them with no prejudice. Yes, Gamera vs. Gyaos remains a lesson for our time, even as it features men in rubber suits beating each other up.