In the seventh year of the apocalypse, humans retreated to the underground city, and mechas were the only weapon against the zombie wave. Levi is a low-level technician at the seventh maintenance station. His daily job is to dismantle the core parts of scrapped mechas and exchange them for survival supplies on the black market. He has a secret that no one knows - whenever the wrong mecha core is dismantled, time will go back three seconds. Until that day, he was dismantling a mecha he had never seen before in an abandoned satellite station. Three seconds later, there was a intact corpse in the mecha cabin, holding a piece of paper full of coordinates in his hand. Black marketeers, military agents, and the woman who claimed to be from three days later were all eyeing him. Levi discovered that every time he went back in time, he was rewriting the entire apocalyptic future.
