Shugo Chara Jewel Joker Vol. 2 manga

Amu is a girl on a secret mission at Arcana Academy. During her pursuit of the X Eggs, the Humpty Lock changes shape, and Amu’s Character Transformation becomes more powerful. While new mysteries continue to emerge, the phantom thief Mirage Lynx steals one of the Arcana Jewels from Heart Dorm! Amu faces a challenge, but she is not alone—help is on the way from familiar friends…