[A laid-back nobody at first, a scheming mastermind later] + [Not a saintly do-gooder] + [Absolutely not a saintly do-gooder]
College student Li Yaozu was tricked by his father into a trafficking den during his junior year. He escaped only because someone managed to get out and call the police. He never went home again, instead working his way through college. But as soon as he entered the working world, his own cousin tricked him into going to the Myanmar border region.
What he endured there was like being a prisoner in a modern-day POW camp. When they had squeezed every last bit of value out of him and were about to dispose of him like livestock, he offered his soul to every god and demon in the world, hoping to drag all the wicked down into the boundless depths of hell.
He thought it was nothing more than a vicious curse uttered before his death. He never imagined his plea would be answered.
He gained an immortal body, at the cost of having to offer up a wicked soul to the owner of that mysterious voice every full-moon night. And that very night happened to be a full moon.