A little boy named Ichiro lives in Tokyo's suburban area. He suffers from being a lonely little kagi-ko (latchkey child.) so, to pass the time until his mother gets home from work, he sits back, closes his eyes, and uses his vivid imagination to travel to Monster Island. 

He fantasizes about meeting and befriending Godzilla's son Minya, who is able to speak intelligible Japanese. He dreams about how Minya must fight a bully monster named Gabara, (the same name as the bigger boy who's been tormenting Ichiro!) and when he is kidnapped by bank robbers, his imaginary friend gives him the courage to fight back and he gets away. Sorry, there really isn't much more than that!