You spent three years guarding the frontier. When you returned, you found that every mech on Earth had broken down, and you had become a public enemy.
[100% repair failure rate! Zhou Rang, humanity's last S-rank mech mechanic, has been exiled to the wasteland.] The next second, he binds himself to the [Chinese Heroes System]. Step on a piece of scrap metal, and an ancient god of war awakens. Tighten a screw, and a mech's martial spirit activates! Everyone else needs a core engine to pilot a mech. The mechs Zhou Rang touches get up and start killing on their own.
When alien species invaded the stars and humanity was on the brink of despair, Zhou Rang dragged in a million-strong army of mechs salvaged from the wasteland and crushed the battlefield. The public enemy of yesterday? Get on your knees and call him ancestor.