Episode Summary: It is the last day before Winter Break, and Yuu, the teacher, is telling them to have fun, but to be cautious about accidents that can happen at any time; he specifically points this out to Amu. After school, the female Guardians are having a day on the town, and Nadeshiko and Yaya are waiting for Amu under the city Christmas tree. Yaya is her usual hyper self and wants to just have fun, but Nadeshiko says that their goal is to buy things for a party. When they are arguing, Su notices Utau on a public television; and Yaya says that she is an ex-model and now a pop idol. As Amu marvels at her beauty, Utau is at dance practice, where she is scolded for not dancing with enough soul. When Yukari, her manager, states that Utau cannot dance like that, and guesses that Utau does not care what happens to Ikuto; this sparks Utau’s anger and she starts up practice again.
At Easter Company Headquarters, Yukari states that she will be able to find the embryo soon thanks to Utau’s magical singing. Yukari and the president are talking about Utau’s problems when Yuu walks in; he says that he is getting use to the acting character as a teacher, and that everything is going as part of the plan. Yuu states that in his position as a teacher, finding the embryo will be easy, but Yukari retorts that she will find the embryo with Utau’s singing. The president interrupts them, saying that it does not matter, the only thing that matters is finding the embryo for their lord; it is now nightfall, and Amu is running home due to it’s lateness. In an effort to get home faster, Amu uses a shortcut, which makes their return later. On the way home, Amu gets lost and hears the sound of a violin; Amu goes to check it out and sees a rock band, but that is not the sound that captivates her. She runs toward the sound, and sees Ikuto.
She spots Ikuto and notices that unlike the other band, Ikuto’s music is sorrowful; when Ikuto spots her, he packs up to leave. When Amu tries to get him to play by the other band, he states that he is not into playing for people, and he asks her to keep it a secret. He gets in real close and asks her, and Amu gets all flustered. When Ikuto starts to walk away, Amu asks him to play again, for his notes were pure. Upon hearing this, Ikuto pauses and is touched, but states that they are enemies; and that the Easter Company is getting serious. Back at the Hinamori residence, the charas are talking about Easter Company and wondering about it; Amu notices that even though Ikuto is an enemy, he is a nice person.
She wonders what kind of guy Ikuto really is, and falls asleep; the next morning, Amu’s family is being eccentric as usual. Ami is singing and her parents are cheering and video taping. Amu notices that the song Ami is singing is Utau’s hit song, and asks Ami if she likes it; Ami responds by stating that she wants to grow up to be just like Utau. Amu looks at the CD cover and remembers seeing Ikuto and Utau together, and wonders if they are dating. Back at Easter Company Headquarters, Ikuto and Yoru are on the roof, Yoru is playing with a yellow ball, and Ikuto is laying looking at his Humpty Key. He remembers what Amu said the previous night when he is interrupted by Utau.
Utau gives Ikuto a hug and requests that they meet that night because it is Christmas Eve, but she is interrupted by a message from work. As she leaves, she states that she will escape at eight, and that she will be waiting, so Ikuto has to be there. On her way out, Yuu stops her and says that a Christmas Eve date is romantic. Yuu then walks toward Ikuto, and he says how brave she is, that she would do anything for him. He says that she falls into the darkness for Ikuto, and wonders if Ikuto always give her the cold shoulder. Ikuto starts his leave and Yuu says that Utau will work for him only; back at the Guardian Garden, they are putting up decorations and laying out a feast.
The charas present their food, Su made a brilliant cake with Miki’s design; when Ran is asked what part she did, she states that she cheered. Before they feast, Yaya has brought costumes for everyone, Kukai is a reindeer, Nadeshiko a Santa, Yaya a bunny, Amu a female reindeer, and Tadase a lion. They begin the celebration with a bang, and enjoy Christmas food, chariokee, carols, and drinks served up by Amu. Around eight, Utau makes a break for it as Amu starts her way home. When Amu and her charas are reflecting on the party, Ran spots an X-egg’s presence; they run towards it and find that the band at the park have all turned to X-eggs.
As the group investigate the scene, and Amu spots Ikuto standing amongst the X-eggs; all the while, Utau is waiting for Ikuto at the city Christmas tree. When Amu is about to approach Ikuto, he forcefully tells her to stay away, and reinforces it with chara power. When Amu regains her composure, Ikuto is nowhere to be found, along with the X-eggs. The city clock then chimes, and Ikuto, Amu, and Utau look up in the sky leaving a sad ending to Shugo Chara! – 12 “A Sad Christmas Eve!”.