Hatsujou Inbo ~Uzuku Jukutai wa, Sono Yokujou o Osaekirenai~

Kashima Takeo visits his wife's family home with their newborn baby during the Golden Week holidays. After dinner, he goes to the restroom and notices that the door to his in-laws' bedroom is slightly open. Curious, he peeks inside and sees his mother-in-law touching herself. His wife has gone to bed with the baby, and his father-in-law is too drunk to notice anything. Takeo becomes aroused and sneaks into the room to touch her. They engage in sexual activity while his father-in-law is asleep in the same room.