Yukio, Ai's younger brother, is staying at Ai's house for a while for his new employee training. When they start living together, the brother-in-law gets turned on by his sister-in-law wearing a tank top with her breasts exposed and a thong! One day, while Ai is taking a nap, her brother-in-law, who is excited by her thong ass and can't hold back, attacks her. Ai resists, but her brother-in-law's back pistons, which are shaking his hips as much as he can, make her pee and climax...