Shugo Chara! Jewel Joker

Sugar and spice, and everything nice—that may be what girls are made of, but Amu Hinamori is so much cooler, especially now that she's left behind her days at Seiyo Elementary and became a middle schooler! After transferring to Arcana Academy on a special assignment, her role as the Joker Guardian is to intervene in a crisis that is causing students to lose hope and confidence in themselves. But she has another, more important secret mission: to retrieve the all-powerful, mysterious Arcana Jewels.

(Source: Kodansha USA)