Teito Klein is a former slave sent to attend the Barsburg Empire's military academy due to his ability to use Zaiphon, a type of Supernatural power. The ability is rare, and thus highly prized. Teito is an amnesiac and doesn't remember anything of his origins—what he does learn of his past comes from his recurring and often traumatizing dreams.

After a Jahr at the academy, Teito takes the graduation exam; it is notoriously difficult, with a pass rate of one in twenty-five. Teito and his best (and only) friend, Mikage, pass easily. That night, in their shared dorm room, they each promise to...