Gakuen Alice (2004)

Mikan Sakura is a normal 10-year-old girl. Optimistic, energetic, and overall a very sweet child, Mikan is the complete opposite of the aloof, intelligent, and somewhat cold-hearted, Hotaru Imai. Despite their glaring differences, the two girls have been best friends for a very long time. So when Hotaru suddenly transfers to Alice Academy, a prestigious school in the city, her best friend is devastated—especially when she hears of the horrible rumors regarding the academy's harsh treatment of students. Beset with worry, Mikan runs away to see her best friend!