1x13 - Shugo Chara!

Amu and the Guardians go to a live New Year's concert where Utau will be performing. While waiting, the Guardians realize that the Easter Company is the sponsor of the concert. Amu also sees Ikuto and follows him into a back area where she inadvertently overhears a conversation between Nikaidou, Yukari, and another person discussing the events that took place on Christmas Eve. As the concert begins, everything is going well until Utau sprouts tiny batwings and four X Eggs appear. The concert ends when part of the scaffolding above the stage falls due to the shenanigans of the Guardian Characters. Amu transforms into Amulet Heart and purifies the X Eggs, but not before Ikuto Character Transforms into Black Lynx and shatters one of the eggs. Amu learns what happens when someone's Heart's Egg is destroyed.