In the S4 Selection of the Beauty Class, "the first ever sister showdown in the history of Four Star Academy" has garnered great interest. Challenging current S4 member Yozora Kasumi is her very own little sister, first year Mahiru Kasumi. Mahiru has been working hard all this time in order to surpass Yozora. Has the time come for her efforts to finally bear fruit--!?
美組のＳ４決定戦に、世間は『四ツ星学園しじょうはつの姉妹対決！』と大もり上がり。今のＳ４である香澄夜空にちょうせんするのは、夜空の妹である１年生・香澄真昼。真昼は、夜空をこえるために今までがんばってきた。そのどりょくがついに、実る時が来るのか――！？
