Soun, Genma and Ranma are all visiting a local temple to assist with the re-sealing of an ancient, evil Oni. The priest attempts to use the seal but Happosai chimes in and unintentionally destroys the seal. The oni is freed and goes around possessing people and committing misdemeanors. It eventually possesses Kasumi, and unable to strike at her, Ranma places a seal on her head to release the oni. The oni is resealed into the box, only to break free later.