Year Seven of the Kowa Period, in the former Hokkaido Block occupied by the Neo-Britannian Empire, live mercenary brothers known as the Nameless Mercenaries. The eldest, Ash, has excellent athletic ability and advanced Knightmare Frame controlling skills, while the youngest, Rozé, is clearheaded and oversees intel gathering and devising strategies. Due to an impregnable wall of energy called the Situmpe Wall, for four years the 100th emperor who stopped the Black Knights' liberation plan, Callis al Britannia, has been trying to plunge the world into chaos once again with the help of his servant, Norland, and his Einberg Knights. Upon receiving a request, Rozé and Ash, along with the Seven Shining Stars resistance group confront the Empire to recapture Princess Sakuya.