Now that he has reached the age of manhood, Manabu has begun to be interested in his stepmother, Kaoru. Her 178cm height and F-cup breasts... her feminine charm that the girls in his class don't have, and her gentle way of treating Manabu, draws the affection of Manabu, who is not related by blood, even though she is his son. One day, Kaoru returns home from moms' volleyball practice and takes a shower as usual. Seeing this, Manabu sneaks into the dressing room and picks up the clothes she has taken off. The sweat-soaked practice clothes and the fragrant smell of her panties make Manabu lose himself in fantasies. Then, suddenly, the bathroom door opens and Kaoru sees them...