Set in the distant future, this school fantasy story depicts a world where pollution-contaminated creatures have taken over the land, compelling humanity to reside in isolated mobile cities known as Regios. Zuellni is one such city, functioning as a self-contained school where freshman Layfon Alseif has recently enrolled. Layfon reluctantly becomes a member of the 17th Martial Arts Studies Unit, which is led by third-year student Nina Antalk, and sets off on a series of adventures. An original side story that places greater emphasis on Nina.