Michika Yagi, a married woman and mother, heads to a concert with her husband and son to see "Puripuri Princess Z," the idol group that's taking the country by storm this year. The night before, she excitedly dances to their hit songs with her son, looking forward to the event. Suddenly, her phone rings—it's Kenichi, her younger sex partner she met at her part-time job. On the day of the concert, Michika breaks her promise to her husband and son, inviting Kenichi over to their empty house. That night, she makes a choice that will change her life forever.