My Sister Exposed My Identity As A Villainous Godfather - Chapter 4

In the winter of Taikang Year 3, a girl pays a visit to her future in-laws, the Ning Family of Beiliu, Yangcheng.

After her engagement was denied, the girl decided to hang herself in front of the Ning Family to show them her sincerity.

When the girl who had died opened her eyes once more, many people’s fates were changed forever.

- Description from Novelupdates

Rhian Locke only wanted strength.To face the monster that slaughtered his parents while he watched, helpless.“I never asked to be your savior. So why should I care?”All he hoped for was to reach a decent rank, hunt that beast down, maybe become a monster hunter, and retire in peace.“I’m not a slave to the gods. I don’t exist to do their bidding.”But the world had made its decision long before he was born.“Patterns are meant to be broken.”------“Boy, I’ve bathed in the blood of your kind. I’ve crushed those stronger than you.”Lightning cracked across the sky. A hammer flew to the hand of a god.“I won’t let a deceiver’s spawn and a whore’s bastard son, stand before me and declare my end.”Rhian stepped forward, blood trailing from his mouth, eyes locked.“I’m not here to declare your end,” he said coldly. “I’m here to fulfill it.”....

He—an enigmatic and cold-blooded soldier with a mysterious background.
She—a ruthless and bloodthirsty spy.

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.