A sister dozing off in front of her brother. Seeing her unguarded state, the brother, despite knowing she's his sister, can't help but get aroused and starts masturbating. The lewd pranks against the sister who doesn't wake up gradually escalate. But when the sister finds out, she is disgusted. Still, the kind-hearted sister can't bring herself to hate her brother and says, 'It must have been because you were too pent-up that a demon possessed you,' and offers to help with the masturbation...!
