Rebirth in the Apocalypse: I Work as a Cow and Horse for the Underworld

It's not a cool article, so don't read it if you don't mind. The first part of the seven-part series, the main content of this part revolves around the story of the protagonist Zhou Chen being reborn and returning to the pre-apocalyptic world, obtaining the underworld system, becoming bigger and stronger step by step, and ultimately saving mankind.