Lustful son-in-law had incest with his mother-in-law while his father was fast asleep

“May I ask Kenichi Kun… Will you ground me for a month before the trip?” Suddenly my father-in-law asked me, and I was confused. I was supposed to go on a hot spring trip without my family's water, but my wife took advantage of me to be my mistress. However, my wife is not interested in having children and gets rejected no matter how many times I invite her … She finally got drunk. After abstaining, I was in pain and couldn't sleep. I was wandering around the motel room in the middle of the night to distract myself when I happened to witness my mother-in-law taking a bath …