Angelic Layer 

In the future, the most popular game in the world is Angelic Layer. Contestants must raise and train their own 'Angels' (or fighting dolls) to compete in tournaments. Enter Misaki Suzuhara, sixth grade Angelic Layer prodigy. With her speed-type angel, Hikaru, many people think Misaki stands a chance at winning the championship. She'll have a lot of help along the way, but the road to victory will be not be an easy route, especially for someone as young as Misaki. (Source: TOKYOPOP) Note: Includes two extra chapters.