Plot Summary: In the distant future, a polluted world has been overtaken by havoc-wreaking creatures called filth monsters. Humanity, having been forced to relocate itself, must live in isolated mobile cities called Regios. A mysteriously skilled fighter named Layfon Alseif enrolls in the Academy city of Zuellni and is immediately noticed by Nina Antalk, leader of the 17th Military Arts Unit. He then reluctantly joins her squad, uncertain of what future awaits him and his new teammates within the city as well as the impending dangers in the midst of a plagued world.