Summary
From Tokyopop:
Yuuichi Tate is overjoyed: He gets to go to a brand new high school. Of course, then he just happens to find out the school he choose is under frequent attack by strange creatures called Orphans, and the school set up a special task force of female members called HiMEs, using various elements as their powers, to battle these invaders. Thats not all, though. Each member of the HiME task force has their own, unique Key, another person whom, upon being discovered, can team up with the HiME to create a Child, a combative unit specifically needed to effectively battle these Orphans. And with Yuuichis luck, he just happens to find out hes not just the Key for one of the HiMEs, but for two... Two highly competitive, rival schoolgirls. And thats only the start of the trouble.
More details