Ultra Maniac

From Viz:
At first glance, Nina Sakura seems like a typical teenage girl. However, she's actually a transfer student from a witch school! Now enrolled in a Japanese middle school, Nina is hoping to improve her grades, make some friends, and practice love spells on her unsuspecting new classmates.

Shy Ayu Tateishi has just made a new friend at school. But this new friend, much to her surprise, is no ordinary classmate. Nina Sakura may look like a normal middle school girl, but she's got a big secret.
She's a witch.
Or, rather, she's studying to be a witch. And apparently, she's not doing her homework. Her spells are devastating in their ineffectiveness and often result in the most embarrassing situations for poor Ayu.
But things wouldn't be so bad if Nina's sorcery didn't make Ayu look silly in front of the one boy she secretly adores. All she wants is a simple love potion. What she gets, however, is a new best friend who almost flunked out of witch school!