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

"Who is that person planning on?" Ichiro muttered in the bath. It's the night my wife was traveling and was away. My sister-in-law Yumi has arrived. He was confused by the sudden visit that he couldn't grasp his intentions... "Shall we let you flow your back?" Then came the naked Yumi. Yumi seemed to be thinking of seducing Ichiro and using it as an outlet for her sexual desires. You can't betray your wife. What's more, my sister-in-law was my partner. Ichiro desperately tries to use his rationality to reject him, but Yumi gives a seductive smile and brings her body closer to her...