Shugo Chara!

Others view Amu Hinamori as a "cool and spicy" girl, however she is actually timid and easily scared. The next morning, after wishing for the courage to be her "would-be" self, discovers three colorful eggs—red, blue, and green—in her bed. At school, the eggs draw the attention of Tadase Hotori whom Amu develops a crush on and confesses to in front of the entire school after a Character Change. However, Tadase rejects her. Others are also interested in the eggs as Ikuto Tsukiyomi and his Guardian Character, Yoru, attempts to steal them. One of the eggs hatch and Ran, Amu's Guardian Character, emerges to help Amu out and along with the Humpty Lock, stolen by Ikuto earlier, Character Transforms into Amulet Heart.

Nadeshiko Fujisaki invites Amu to tea at the Royal Garden with the Student Council Guardians, along with a message from Tadase that he will tell her about the Heart's Egg. During P.E. class, the blue egg begins to hatch, unbeknownst to Amu and Ran, and Miki, Amu's second Guardian Character, peers out. However, after seeing Amu and Ran in an argument over a Character Change, Miki runs off. The two soon discover Miki and give chase. Miki warns Amu that if she does not believe in her Guardian Characters, they will disappear. When Amu meets with the Guardians, Tadase, Nadeshiko, Kukai Soma, and Yaya Yuiki, she discovers that they also have Guardian Characters and they invite her to join. However, Amu refuses and runs away. Amu encounters a third-grade admirer, Suzuki, and an X Egg forms from his heart's egg. Amu transforms into Amulet Heart and purifies the X Egg.

Nadeshiko tells Amu that the two should become friends. However, Amu sees it as a trick to get her to join the Guardians. Nadeshiko convinces Amu to go together to Tadase's house. The two meet in the school's kitchen to make some snacks. Nadeshiko warns Amu about using the word "Prince" around Tadase. Ikuto interrupts the two and attempts to steal the last egg. However, the egg hatches and Su, Amu's third Guardian Character, emerges. While Amu waits for Nadeshiko at a park, she is surprise when Tadase arrives instead. Panicking, she inadvertently gives him the snacks containing a love note inside. Amu sneaks into Tadase's house to retrieve the note, but discovers that Tadase Character Changes into someone set on world domination whenever he hears the word "Prince". The next day, the Guardians announce Amu as their new member, the Joker.

Amu protests to the Guardians about making her a member. However, the Guardians explain that while they have to do boring work, the Joker's responsibility is dealing with her own affairs and handling the X Eggs. Amu receives the Humpty Lock and a pouch to carry her Guardian Characters. Nevertheless, Amu refuses wearing the cape that the Guardians wear. At home, Ikuto drops by and gives Amu a bag of cookies and candies as a way to make up, but warns Amu to not search for the Embryo or they will be enemies. The next day, Amu chases after an X Egg, but bumps into the new teacher, Yuu Nikaidou, and loses track of it. The egg hatches into an X Character and finds Amu at the school's planetarium were Amu Character Transforms into Amulet Heart and purifies the X Character.

Nadeshiko and Amu watch Kukai's soccer team practice where Amu encounters Yamada, one of Kukai's teammates. However, when the coach announces the starters for the next match against a top ranked team, Yamada does not make the list. At the match, Yamada sneaks away while feeling that he cannot match Kukai's abilities. Nikaidou takes advantage of Yamada's feelings and extracts Yamada's Heart's Egg, which turns into an X Egg and hatches into an X Character. Amu transforms and is able to purify the X Character just in time for the coach to declare Yamada as a substitute one of the starters. With Yamada's efforts, the team is able to tie the game.

Amu accompanies Yaya to the guardian's ballet class. While there, Amu meets with the class's prima, Maika Himekawa. During practice, Maika sprains her ankle and Yaya is chosen to be Maika's stand-in for the upcoming performance. While thinking about Maika, Amu goes to the planetarium she discovered in episode four and meets with the planetarium's caretaker. Meanwhile, Nikaidou meets with Ikuto on the street and informs him that that Maika's egg may be the Embryo, but if it is not, Ikuto will need to clean up. During dress rehearsals, Nikaidou extracts Maika's egg, but it turns into an X Egg and hatches an X Character. Yaya Character Changes to combat the X Character but her attack is reflected back to her. Amu does her first Character Transformation with Miki and the two become Amulet Spade. As Amulet Spade, Amu is able to purify the X Character.