Raki, Aine and Mio find themselves in an unknown location, that just happens to be at another idol school. The three idols are introduced to Yume Nijino of Four Star Academy and her friend Koharu Nanakura. Although the idols are able to sense that each of them is a talented idol, neither group have heard of each other. With seemingly no way back to Star Harmony Academy, Raki, Aine and Mio decide to stay with Yume and Koharu at Four Star Academy and see how they do Aikatsu. As luck would have it, Yume's friend and fellow S4 idol, Mahiru Kasumi, is holding a fashion show with her premium rare dress, and Raki is determined to see it for inspiration. Meanwhile Yume and Mio believe they have a perfect opportunity to learn from each other's Aikatsu and shine brighter as idols.
らきたちが光る扉をくぐった先――そこはなんと、別のアイドル学校・四ツ星学園の前だった！どうやら元居た場所には戻れなくなったらしい……。四ツ星学園のアイドル・虹野ゆめに案内され、香澄真昼のファッションショーを見学することに！
