At the Barsburg Empire's Military Academy, students are trained to become skilled warriors and serve as the newest soldiers of the empire. Every year, 500 students take the graduation examination, with only 20 being able to pass and earn the notable title of "begleiters," similar to assistant executive officers. These individuals are equipped with "zaiphon," unique abilities provided by the Divine Spirit that differ for each person to combat their opponents.
Teito Klein, the favored student of the academy's chairman, is ostracized by his peers for his previous enslavement. Despite struggling to remember important memories, Teito's loyal friend, Mikage Celestine, supports him. After finishing the test, Teito recalls fragments of his forgotten past, triggering him to violently attack the chief-of-staff, Ayanami.
Teito faces the consequences of his disobedience when he is imprisoned and interrogated. With the help of Mikage, he manages to escape and takes refuge in the Barsburg Church, located in the empire's Seventh District. While avoiding the military's pursuit, Teito gradually discovers the hidden memories within him and a formidable force that lurks in the empire's shadows.
Additionally, Volume 17 includes a standalone story, "Seven Ghosts (pilot)."