Zero

At the beginning of the series, Zero is a thirteen year old wizard-in-training. He is taking the magic exams with his partner, Ichî. They planned on getting the Crystal Pearl and winning the Magic Exams, but there plans change when Nina, a human girl, swallows the pearl. When the Magic Examiners here about this, they inform them that a potion to remove the pearl won’t be available for another six months, by the time the exam is over. Much to Zero’s aggravation, Ichî says that they will have to protect Nina until the end of the exams.

Zero often argues with Nina, and calls her an idiot. This causes Nina to often physically hurt him. He and Ichî enroll in Nina's school to make sure she is safe at all times, and have secretly created a magical space in her closet where they live. Many other examinees try and attack Nina to obtain the pearl, but Zero and Ichî always end up saving her. As time passes, Zero begins to develop feelings for Nina.

Zero was born into a rich family, and when he was ten years old, his older brother, Jeff, was engaged to a poor girl. Zero met her step brother, Ichî, and witnessed his power. Right away he wanted to enter the Magic Exams with Ichî. Originally Ichî planned on using Zero, but Zero was to naïve to notice, and was willing to do anything it took to become Ichî’s partner. Eventually, Ichî and Zero’s powers are combined to defeat a powerful enemy, and the to become the best of friends. They eventually enroll in a Magical Cram School to prepare themselves for the Magic Exams.

(Source: Wikia)