Raki Kiseki is a second-year middle school student who transfers to Star Harmony Academy to become an idol. However, when she uses an Aikatsu Pass she received from her older sister (an Aikatsu engineer), something mysterious happens. Numerous doors appear before her, and upon opening them, she encounters Aikatsu idols she was previously unaware of, such as Yume Nijino (from Aikatsu Stars!). Raki vows to design her own premium dress and perform in it on stage.