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... more>> he choose is under frequent attack by strange creatures called ''Orphans'', and the school set up a special task force of female members called ''HiME''s, using various elements as their powers, to battle these invaders. That's 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 Yuuichi's luck, he just happens to find out he's not just the ''Key'' for one of the HiMEs, but for two... Two highly competitive, rival schoolgirls. And that's only the start of the trouble. <<less

Mashiro-hime has just transferred to the all-girls school, Garderobe...but little do the other students know, she's actually a boy. Desperate to escape an all-boys school... more>> where he was looked down upon, he disguised himself as the late Mashiro-hime to get in. Unfortunately, due to "her" royal status, members of an organization known as Shwarz are trying to assassinate him, and all the while, he's trying to break his Contract with Arika Yumemiya, who unexpectedly became his Otome to protect him from a member of Shwarz. <<less

Centers around a platoon of the Earth Federation Forces set on the earth at the end of the One Year War.