重生廢鐵機甲:被瘋少女打到進化

Reborn as an empty mech. No flesh, just metal—but my battle instincts remain. I've saved this world from monsters. Now I'm scrap, target practice for a reckless girl who rides me hard and never cares. She overheats my barrel daily. I thought retirement was bad. She's just the beginning. What happens when the real enemy returns?