Ichiro Miki is a child living in the industrial district of Kawasaki, where his parents' constant struggle to make ends meet often leaves the schoolboy alone. Constantly teased by a bully nicknamed Gabara, his only friends are toy consultant Shinpei and fellow classmate Sachiko. Ichiro turns to escapist dreams of Monster Island where he befriends the equally bullied Minilla.
Searching for his brother, Ryota stows away on a boat belonging to a criminal alongside two other teenagers. The group shipwrecks on Letchi island and discover the Infant Island natives have been enslaved by a terrorist organization controlling a crustacean monster. Finding a sleeping Godzilla, they decide to awaken him to defeat the terrorists and liberate the natives.
After a meteorite unleashes a three-headed beast upon Tokyo, Mothra tries to unite with Godzilla and Rodan to battle the extraterrestrial threat.
