Driven off the surface by armored magical insects, what is left of humanity lives in floating cities defended by airborne wizards. Kanata Age, once celebrated as the Black Master Swordsman of the elite S128 team and now branded its traitor, is handed the worst posting available: instructor to E601, a cadet squad losing badly enough to face disbandment. His three students are squad leader Misora Whitale, the soft-spoken close-combat specialist Lecty Eisenach and the self-styled goddess of sniping Rico Flamel.