Set in Kisshou City, one of the few remaining oases amid a lifeless, post‑war wasteland, residents salvage and reassemble humanoid weapons known as “Legacies.” When a gang of bandits arrives, intent on uncovering the secrets hidden within the Legacies, the mayor deploys the long‑intact robot Ω99 to intercept them. A teenage boy named Yamato, an ordinary gamer who has no idea about the city’s crisis, is unexpectedly chosen to pilot the robot.
