PTA Mama (43) Mariko Koto, a young teacher who is the eldest son's homeroom teacher, and an hour-long karaoke secret meeting adultery to eliminate frustration.

Mariko serves as PTA's board member at a junior high school attended by her eldest son. One day, at the suggestion of the president, he decided to launch a school festival including his homeroom teacher. It is popular at the izakaya of the Daiichi-kai, and it goes to the karaoke of the second party. In such a situation, Namariko's frustration with her desires turned her attention to the job of her eldest son. Take advantage of older experience and motherhood to seduce closeness. Eventually, they had an affair with each other.