While scavenging to survive on the abandoned No. 99 Junk Planet, young Lin Xiao unexpectedly digs up Old Ghost, the AI of a Titan-class mecha that has slept for two thousand years. He is dragged into a many-sided conflict between the Empire, pirates, and mysterious hunters, and flees alongside imperial female engineer Su Bing. Through harrowing dangers, they gather Titan components and keep breaking through their limits. Facing a mechanical threat that could destroy civilization, the boy abandons his bottom-rung life and pilots the Titan mecha toward a final showdown at the heart of the galaxy. Thus begins an adventure spanning the stars, as a scavenger takes up the burden of protecting the galaxy.