Koukaku no Regios is a post-apocalyptic anime series that follows Layfon Alseif, a young warrior with a mysterious past. Set in a world where humans live in mobile cities to escape pollution and monstrous creatures, Layfon joins the 17th Military Arts Platoon in the city of Zuellni. The series explores themes of survival, friendship, and redemption as Layfon navigates the complexities of his new life while uncovering secrets about his own abilities.