Gamba, a town mouse with a brave spirit decides to go on an adventure to discover the ocean. On his way, he meets a troubled child mouse, Chuta. He says his family and other mice on a nearby island have been killed by a clan of weasels, led by the terrifying Noroi. Gamba promises to save the island, his family and the other mice. He and his friends team up to defeat the evil Noroi and his clan.