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.

An inventor and his family try to raise funds to feed a giant monster named Daigoro so that he doesn't shrink. Meanwhile, a meteor lands into the sea bringing with it another giant monster named Goliath. Will Daigoro be able to stop Goliath?