Yoshino attends a PTA meeting for his son's new school term, where he meets Ayano, the mother of Mari-chan. The two are unexpectedly appointed to the board. Yoshino is immediately drawn to Ayano's friendly and elegant demeanor. However, this is merely a facade; Ayano's true nature is that of a woman who desires what belongs to others. One day, while working in the gym storage room, their conversation turns to romance. Ayano, reminiscing about her youth, makes a suggestive proposal to Yoshino: "Why don't we kiss here?" When Yoshino tries to deflect, Ayano forcefully kisses him. From that day forward, Yoshino becomes entangled in a year-long, intimate PTA affair with Ayano, lasting until his son's graduation.