Go for it! Seiichiro!
During attendance day, the Guardians announce that the school will be participating in a choir contest. Amu ends up with the lead part while Marimo is chosen as the pianist. Because Seiichiro is a bad singer, Marimo helps him practice by playing the piano with him, and tells him about her dream to keep playing the piano. During rehearsal, Marimo makes a simple mistake and Saaya and her group criticize Marimo for it. Marimo becomes upset and excuses herself from the rehearsal. The next day during the competition, Marimo does not show up. Because of Saaya's earlier criticism, Marimo's Heart's Egg turns into an X Egg and hatches. The Guardian Characters sense this and the Guardians, along with Seiichiro, go looking for Marimo. With Seiichiro's unwitting help, Amu transforms into Amulet Heart and purifies the X Character. The choir performs successfully, and Amu Character Changes to sing her solo.
Aired 16/08/2008EP 45 - Go for it! Seiichiro!
Shugo Chara!
Amu Hinamori is a 5th grade transfer student who is fashionably cool, tough and independent. Despite this, she is also a girl who seems unapproachable, both at home and at school. In reality, the "Cool and Spicy" role she plays is just a facade that she unconsciously plays. With her guardian characters, she fights the Easter Company who is extracting people's eggs to create X Eggs & X Characters in search of a special egg called the Embryo.
(Source: Crunchyroll)