The alien bugs invaded, and humanity retreated to the "Ark" mobile fortress. Four years ago, hero Kevin piloted the mech "Silver Scar" to defeat the swarm, but retired after his entire squad fell. When the bugs returned, Kevin reapplied—only to show 0% compatibility. Spy Marshal Sam framed him for treason, sentenced him to death, and sent his mech to the scrapyard. As the swarm breached the gates and Kevin faced execution, "Silver Scar" self-activated, rescued him, and synced at 100%. Kevin repelled the swarm, and the whole city witnessed the war god's return.