Nakajima comes to his friend Shingo's house to stay the night. Shingo's mother Jun warmly welcomes Nakajima. At night, Nakajima happens to see Jun getting changed in the dressing room and is captivated by her charms. One night, unable to fall asleep, Nakajima is on his way to the bathroom when he sees Jun lying defenseless in the living room. Driven by temptation, Nakajima lifts her skirt and, unable to contain his excitement, masturbates. Jun then wakes up and playfully provokes Nakajima. The two enter into a forbidden relationship and spend an intense night together.