The story revolves around a young man named Teito Klein, who is receiving education at the military academy of the Barsburg Empire. Former hostage from a captured state, he was admitted to the elite institution because of his unique ability to wield a Zaiphon - the local equivalent of magical energy. Due to the harsh wartime conditions, Teito has no memory of his early years. However, his slave past is not erased from his memory - nor are the mentors and students from the "core nation" surrounding him at the Academy.