Kyosuke ends up staying overnight at his classmate Kazuma's house to study for exams. There, he meets Kazuma's mother, Kayoko, and is completely Kokoro by her voluptuous body and her sultry, fragrant sex appeal. That night, Kyosuke is woken up by a strange noise and sneaks out of the room... There he sees Kayoko straddling her husband, shaking her hips in a frenzy. Having witnessed the whole thing, Kyosuke is so excited that he can't sleep at night. The next day, he meets Kayoko, still in a state of turmoil, but he can't get the lewd behavior of the previous night out of his head...