In a post‑apocalyptic world overrun by mutated beasts known as Limbeekoon or Filth Monsters, humanity survives inside massive mobile cities called Regios. To defend themselves, citizens learn to wield special weapons called Dite, channeling the power of Kei. In the Academy City of Zuellni, Layfon Alseif hopes to begin a new life and forget his past. However, his history draws the attention of Karian Loss, the manipulative Student Council President, and Nina Antalk, a Military Arts student who commands the 17th Military Arts Platoon. They immediately recognize Layfon’s talents and deem him the ideal candidate to join their ranks. Yet Layfon’s secret past and the unknown powers he carries threaten to resurface.