Kuukai Souma
The upbeat and energetic former Jack’s Chair, he is one year senior to Amu. As the captain of the Soccer Club, he is athletic and has good reflexes. He has graduated, which is the reason he has been replaced.
Once, in the school magazine, he and Amu are mistaken to be a couple, as a student got a picture of him holding Amu after she came out of her Character Change, and lost her strength. Saaya appears to have a crush on him, as when she saw the picture of him with Amu, she was furious.
He and Utau become good friends in both the anime and manga leading to a suspicious Yaya.
In the first chapter of Shugo Chara! Encore! it is revealed that Kuukai has feelings for Utau, eventually his feelings are returned, and the two end up being a couple.