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 big sister (an Aikatsu engineer), something mysterious happens. Lots of doors appeared before her, and when she opens them, she meets Aikatsu idols she never knew before, such as Yume Nijino (Aikatsu Stars!). Raki vows to design her own premium dress and perform in it on stage.

(Source: Anime News Network)