After the supposed death of its 99th emperor, the Holy Britannian Empire broke up, and the areas it controlled finally regained their independence. While most joined the United Federation of Nations, a group aiming to create everlasting peace, remnants of the oppressive empire continue to exist. One such faction, Neo-Britannia, has taken over Japan's Hokkaido island after killing its governor, Juugo Sumeragi.

The Seven Shining Stars, a resistance group in Hokkaido, finds itself at an impasse as it struggles to find a way to defeat the Neo-Britannian Empire. As a last resort, it enlists the aid of the Nameless Mercenaries: brothers Rozé, a genius strategist; and Ash, an exceptional Knightmare pilot. Though Rozé and Ash are Britannian, they have made a name for themselves by protecting the Japanese and killing the empire's officials. With their help, the resistance may finally be able to recapture its territory and prevent another reign of terror.