A new school year begins and Amu wakes up to find a yellow Guardian Egg with a diamond pattern in her bed. Meanwhile, Utau steals more Heart's Eggs during a concert. This results in an argument between Il and Utau's second Guardian Character, El, causing El to fly away. Amu is excited that she and Tadase will be in the same class, but being in a new class makes her nervous. The class gets excited over a transfer student, Rima Mashiro. Ran, Miki, and Su sense another Guardian Character coming from Rima. However, when Amu's unsuccessfully attempts to become friends with Rima, a rivalry between the boys, who support Rima, and the girls, who support Amu, breaks out. The rest of the day fares no better as Amu has trouble capturing an X Egg, nearly hitting Yaya in the process. Amu becomes depressed, and her fourth Guardian Egg turns into an X Egg.
クラス替えの日の早朝、あむの部屋から叫び声が聞こえてくる。何と、ベッドの中からダイヤの模様のついたたまごが出てきたのであった。そんななか、新6年生になったあむのクラスに転校生がやってくる。
