Sayuki visits her parents' house to celebrate her niece's entrance into school. Her mother and sister are out shopping, and only her brother-in-law, her sister's husband, is there. To avoid her brother-in-law, who has been drinking alcohol since noon, she goes into the bathroom to take a shower, but when he comes in, she sees a huge cock she's never seen before! She is pushed down on the bed and her eyes roll back and her whole body convulses every time he thrusts into her...