When Koji returns to his parents' home for the Obon holiday, he is confused to find that his brother and his wife are having a dispute over fertility treatment. That night, he accidentally peeks at the couple having sex, and he can't take his eyes off his sister-in-law, Riho, who is obscene. Riho desperately wants to get pregnant, so she keeps her peeping a secret and begs Koji, who has a child, to cum inside her. He is carried away by his sister-in-law's intense temptation to devour his cock, covered in sweat and hiding from the rest of the family, and Koji can't help but ejaculate deep inside Riho's vagina...