I was aroused by the bold seduction of my girlfriend's younger sister (a female idol), and I continued to cheat on her many times. - Miyu Aizawa

The movie revolves around the protagonist, Kodai, who becomes infatuated with his girlfriend's younger sister, Miyu, a female idol. As they spend more time together, Kodai finds himself drawn to Miyu's charms, leading to a series of clandestine encounters. The central dramatic tension arises from the illicit nature of their relationship, complicated by Miyu's status as an idol and the fact that Kodai is already in a relationship with Mina.