Long ago, an evil demon wreaked havoc upon the world. Though it was sealed away by a powerful monkey monk, over time the spell's power gradually weakened. Coupled with Happosai's meddling, the demon regained its freedom. However, this creature seemed different from the legends—its round, chubby body paired with a foolish appearance sent chills down everyone's spine. Of course, appearances can be deceiving; it possessed the ability to possess others, and anyone taken over by the demon felt an impulse to do evil. During this time, Genma Saotome, Tatewaki Kuno (voiced by Hirotaka Suzuoki), and Ryoga Hibiki (voiced by Koichi Yamadera) all fell victim one after another. Even the usually kind-hearted sister Kasumi (voiced by Kikuko Inoue) got caught up in it. Faced with the gentle and amiable sister Kasumi, the Tendo family found themselves in endless trouble...