Amate Yuzuriha is a high-school student living peacefully in a space colony floating in outer space. When she meets a war refugee named Nyaan, Amate is drawn into the illegal mobile suit dueling sport known as Clan Battle. Under the entry name "Machu," she throws herself into fierce battle day after day, piloting the GQuuuuuuX. Then an unidentified Gundam mobile suit pursued by both the space force and the police appears before her, along with its pilot, a boy named Shūji.