A childhood memory resurfaces for Akane Tendou: a boy named Shinnosuke once saved her from a giant platypus in the village of Ryugenzawa. When monsters start appearing there again, Akane returns to find Shinnosuke grown up, and stays behind to nurse him after he's badly hurt protecting her. Convinced Akane has fallen for her old rescuer, Ranma Saotome chases after her, with Ryouga tangled up in the fallout.