The Game's Extra: Azhriel Odyssey - Chapter 44: Letter.

A supreme expert in the Immortal World had died, and a strand of his soul returned to its original body on Earth. Tang Xiu discovered with amazement that ten thousand years passed in the Immortal World, yet only a single year passed on Earth.

Ruthlessly betrayed by his lover and trusted friends, Tang Xiu found that his soul went back to his previous body on Earth, and, despite he spent 10,000 years in the Immortal World, just a year has passed on Earth and many things have changed. Having an unsurpassed knowledge, Tang Xiu will protect his loved ones and go back to the Immortal World to take his revenge.

- Description from Novelupdates

200 years after the world has ended, the laws of society have long been forgotten.

As his contract-marriage wife, she just wanted to fulfill the mission given by his mother—having a baby. They didn't love each other, so he always used contraception before they got laid. She had been obedient to him, only to find that he had gone too far! He actually didn't care about their child at all! She couldn't stand it anymore, so she handed him the divorce papers and left, noting: “The world is so huge that I can surely find a better man.”Looking down at her, he retorted, “Come on, your purse strings will tighten up first before you find anyone.”

Tired of the schemes and strifes of city life, Bei Feng finally returned to his hometown in the countryside