The Agent of the Underworld

After the protagonist dies, he has no money to bribe anyone and gets stuck between the realms of yin and yang. A seemingly corrupt bailiff, a ghost messenger, secretly helps him exploit a loophole in the System and return to life. The protagonist thinks he has escaped with his life, only to discover that he has become the ghost messenger's proxy in the mortal world, tasked with completing his KPIs. He is forced to get caught up in one bizarre incident after another involving both realms.