Hunting Immortals in Another World

Fu Xiaochen had lived for 2500 years in the cultivation world.
He had done all sorts of sins that one could think of.
He had walked on the path of cultivation for the sake of vengeance. He had fulfilled his dreams and killed his enemies.
But still, he felt empty. And when his beloved wife tried to kill him, that was the end of the line for him.
He ran away from his life and started living in a secluded mountain.
But one day a lady comes to greet him there. That lady gives him a chance to live life in another world. A world where he could get a fresh start.
But the only catch is that he had to do something for her in return.