Since the dawn of mankind, Heaven has been waging a war against the demonic forces of Hell through the use of child soldiers-turned-bioweapons known as "Angels". The year is 201X. In the city of Bethel, when the leader of the St. Abraham's High School Angel Brigade, Hikari Akeldama, begins to unravel the dark truth of the war she's been fighting for years, what she discovers will drive a wedge between her and the rest of the platoon as she tries to find the answer to an age-old question: Is it better to reign in Hell than to serve in Heaven?