In the Century of Darkness, monsters called Vandels dominate the world, and only the Vandel Busters can oppose them. After a squad of Busters falls in combat, they bequeath their magical Saiga weapons to Beet, elevating him to the status of the most powerful Buster ever. Yet Beet aims for more than merely battling the Vandels; he intends to annihilate them and bring an end to the Century of Darkness.