Back to the Apocalypse - Chapter 115

Each stroke of good luck is a triumph over someone else’s misfortune.Jack Grim, the son of two legendary assassins, was born and raised on nothing but coldness, and the skills to spill blood.At seventeen, Jack received his final task as an assassin apprentice under his parents.“Succeed, and you’ll run your own organization — live the life you’ve always dreamed of.”For Jack, it was everything he had ever wanted: the chance to finally become the professional assassin he was born to be.He struck his target at midnight, succeeded, and received everything his parents had promised.But in the wake of victory came a pounding headache, a relentless fever—and then… transmigration.Jack now found himself in Raiden’s body, the keeper of the Book of Ashes, the heart of the Devourer, and the very book the coward Raiden had died protecting with his life.Jack had no desire to live in another world, magic or not. He simply wanted to return to his life as an assassin.But duty had other plans. The balance of this world now rested on his ability to protect the book, and like it or not, the responsibility was his to bear.

Follow Chen Ming as he accepts disciples, establishes a sect, and fights his way in a world that deems him a cannon fodder.
He goes against any common sense using his wits and novel knowhow to finish missions and arm himself against his cruel fate.

- Description from Novelupdates

It was supposed to be a perfect deal in which both parties got what they needed. However, after the child was born, he tore up the agreement with discontent and told her, “Who said that we’d only have one child? I want twins! Twin brother and sister! You’ll continue giving birth to more children until you bore me a pair of twins!”