Rikako lives with her husband and son, Akira. On the surface, it appears to be a happy family, but she harbors a secret she cannot reveal—the existence of her younger boyfriend, Takashi, whom she met on a dating site. He is so much younger that they look like mother and son. Though she knows he is off-limits, she repeatedly gives in to her uncontrollable desires. One day, she discovers that Takashi is actually Akira's classmate. Shocked, she decides to end their relationship, but an unexpected turn of events awaits her.