One night and two days of 1 night and left alone by my wife's sister who suddenly came over

Eriko couldn't stand her husband's domestic violence and cheating, so she ran away to her younger sister and her husband's house. Today, her younger sister, Taichi, greeted Eriko in place of her younger sister, who couldn't go home due to work. After dinner, Taichi invites him to drink some alcohol, trying to cheer him up. After a while, I was relieved to see Eriko laughing brightly, perhaps as if she was drunk, but then after the drinking season was over, Taichi was taking a bath, and there was a incident that had occurred. "I'll wash your back," Eriko, who actually gets dirty when she gets drunk, came in naked. Eriko's hand reaches out to Taichi's crotch as he panicks...