Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Volume 17 Chapter 42

The strongest Demon Lord dies, and reincarnates as a human. Not only that, he because of various incidents turns into the hero’s best friend.

Follow his journey as he tries to help the hero escape his fate, and on the sideline to conquer the continent while he’s at it.

Gu Changge, a noble lady from a wealthy family, is a well-known business legend in Yuncheng, going into business at 15, taking over as President of Gu Group at 18 and becoming Chairman of the family business at 30.
She is murdered by her husband Shao Tianze, just to give his mistress Gu Changle a healthy heart. But a premeditated car accident makes Gu Changge revive in a new guise and settle into an 18-year-old girl, Song Yunxuan.
The new face, young body and experienced soul become her weapons of revenge. In her struggle with the four big families in Yuncheng, can Gu Changge shrink back? Will she open her broken heart again? Can she always head off dangers in power struggles?
Let’s find out if Gu Changge can revenge herself and create glory again.

- Description from Novelupdates

“Chantelle Bently, you’re a murderer! Why are you still alive? You should have been the one to die!”Daniel shoved her away furiously, his face as dark and empty as the black suit he wore.Chantelle was caught off guard and lost her balance, falling hard onto her pregnant belly.The pain was unbearable, and she cried out as her body trembled.Chantelle shook her head desperately. “I told you, it wasn’t me! It was Kate!”In a trembling voice, she pleaded, “Daniel, how many times do I have to say this before you believe me? I didn’t betray your family or the Wilson Group Of Companies, and I didn’t cause your grandfather’s death.”Anger and resentment appeared in Daniel’s eyes as he threw the divorce settlement in Chantelle’s face. “Sign this now! From this day forward, I’ll make you pay a thousand times for everything you’ve done!”The sight of the document struck Chantelle like a dagger to her heart.Her whole body froze as if she had been cast into the icy wastelands of Hell.****Her twin sister framed her, and her perfect family was destroyed on Christmas Eve.Things got worse when her husband handed her a divorce agreement. A month later, rumors spread that she had died in prison from depression.Six years later, she returned with a new face to take her revenge. She was beautiful but dangerous.Daniel felt both devastated and irritated when he saw the mysterious woman. She had the same name as his dead ex-wife, whom he hated most and the one he believed was responsible for his grandfather’s death.Despite his anger, he couldn’t deny the strong attraction he felt toward her.In fact, he was fatally obsessed and addicted to her, and the anger that had controlled him for six years slowly started to crumble.

“Now you see?” she shouted in a mix of annoyance and disappointment. “You can't outsmart Scrients! They're the most intelligent beings across the two realms.”“You're right,” I muttered, averting my gaze with a heavy sigh. “I made a mistake. I was too arrogant to think that a mere human like me could fool them.”—BOOM!!“Heik! Wh-What was that?”“Hmm? I'm not sure. Maybe you should go and ask the most intelligent beings across the two realms. Oh wait, you can't. I killed them all.”______My name is Samael Kaizer Theosbane.On the last day of high school, I got into a fight with a kid I used to bully.It was a stupid, pointless scuffle, and in the middle of it, I tripped and hit my head on a rock.That’s when the memories came flooding in - the memories of another life, of a different world.Suddenly, everything made a twisted kind of sense. I realized two things.First, I was in a game I used to play in my past life.Second, I was a villain. A villain!Not the cool and mysterious kind, either.No, my destiny was to be manipulated and die a dog's death!I was the worst type of cliché: an ungrateful, privileged, insufferable young master. The sort you'd find in those poorly written fantasy stories.The kind everyone hates — a snobby brat from a powerful noble family who thinks he owns the world just because he was born with a silver spoon lodged in his mouth.You know the type. The one the hero beats to a pulp to prove his worth.Yeah, I was that guy.And the hero? The hero was the kid I’d been bullying all this time. The same one I got into a fight with.He was the supposed savior of this damned world.A world teetering on the edge of destruction, beset by wars, calamities, and a grim future that only I knew.And at the end of it all, the final antagonist of the game, the undefeatable boss… the Spirit King, was waiting.But could I even make it to the end?Could I conquer a game where defeat was the only certainty?A game that was now my reality!“Ah, fuck it.”I had no idea if I could, but I sure as hell was going to try.Extorting extras, manipulating main characters, twisting the story to my advantage, stealing the hero’s cheat items, killing villains before they could become threats - nothing was beneath me.Would the main characters be affected? Who cares!Would the story change? Even better!All I cared about was me—my survival, my life, my choices.“I will live this life with no regrets.”…But as I soon discovered, fate was not easily changed.And the price of altering one's destiny was steep.