Natsumi Kitahara is 40 years old. With her husband away, she grows increasingly anxious about the furtive gaze sneaking into her room every night. However, the one responsible for the gaze is actually her son. He secretly sneaks into his sleeping mother's room, gently peels back the futon, licks and touches her body, and sometimes rubs his penis against her as a prank. One day, the mother wakes up sensing someone's presence, mistakenly believing she had merely tossed and turned in her sleep.