Arisa gets excited when she sees the cock bent over by her son Gingin who is masturbating. Even when she gets into the futon, her son's cock doesn't leave her head, and she naturally reaches for her crotch and masturbates. The son, who noticed the gasping voice leaking from her mother's bedroom, also witnessed Arisa masturbating, and the two became a man and a woman. Arisa refuses to have sex for the second time because of her incestuous feelings of guilt.
