Gamba to Kawauso no Bouken

Shijin becomes worried when his girlfriend Nagisa goes missing, prompting Gamba, Bobo, Gakusha, Ikasama, Shijin, and Yoisho to search for her on the South Island. There, they learn of a family of Japanese otters threatened by a wild dog named Black. Meanwhile, Chuta, a severely injured mouse, arrives at Tokyo Harbor and collides with Gamba and Bobo, who are attending a party hosted by Yoisho. Chuta reveals he fled from Devil's Island, where Norio, an evil ermine, has been terrorizing the mouse population.