Kowa Period Year 7, there lived the brothers Roze and Ash, the "Nameless Mercenaries (ナナシの傭兵)" brothers of the old Hokkaido block of the United States of Japan. Known to be undefeated in their operations with Ash's advanced Knightmare piloting skills and athleticism and Roze being the brains with his intelligence gathering and strategizing.
The brothers face their greatest challenge when Japan gets occupied again by remnants of the Brittania royalty calling themselves the "Neo Britannian Empire". Led by Neo Britannia's 100th emperor, Chalice al Britannia, and his Knights of Einberg, Japan is isolated it from the rest of the world with the impregnable "Situmpe Barrier (シトゥンペバリア)" energy wall for the next 4 years. To counter this new Britannian invasion, Roze and Ash accepts the UFN government request to assist the Black Knights' Liberation Plan and the resistance group called the "Seven Shining Stars (七煌星団)" to take on Neo Britannia and rescue Sakuya Sumeragi.
