Set in a world ravaged by mutated creatures known as Limbeekoon or Filth Monsters, humans find refuge in mobile cities called Regios, wielding special weapons called Dite fueled by the energy of Kei for defense. In the bustling Academy City of Zuellni, Layfon Alseif seeks a fresh start to escape his troubled history. Yet, his enigmatic past draws the attention of Karian Loss, the cunning Student Council President, and Nina Antalk, a skilled Military Arts student and leader of the 17th Military Arts Platoon, who sees in him a valuable addition to her team. Torn between his haunting secrets and extraordinary abilities, Layfon faces a choice that could alter his destiny.