Based on a novel by Ayako Miura.
A moon base is destroyed by a spaceship from Zigra which is looking to take over the planet earth to use its oceans for its ocean-dwelling denizens. Gamera must once again come to the aid of the human race while all of Japan roots him on.
Shinji and Masaru spend most of their school days harassing fellow classmates and playing pranks. They drop out and Shinji becomes a small-time boxer, while Masaru joins up with a local yakuza gang. However, the world is a tough place.