Ranma Saotome and the rest of the group are shipwrecked by a storm and washed up on a remote island where Toma, its self-declared ruler, has already carried off every woman among them to fill out his harem. Ranma scrambles to get Akane Tendou and the others back, with Mousse taking an unusually large share of the rescue effort this time around. The island's own terrain turns into one obstacle after another along the way.