MTL - I’m Walking the Career Line In Dog Blood - Chapter 113

Some say reincarnation is a blessing, but for me, it's a dreadful curse. Cursed with endless reincarnation, I've been reborn as a villain 137 times. And all 137 times, I've been toyed with and killed by heroes who are far more cruel than the said villains... If I can't win no matter what I do, then I'll crush those so-called heroes at their very roots. - Quality Fan Translations, Made by Fans for the Fans - Villain Takes Over The Academy

Ziel Grisel (Nijisaki ken) succeed defeated the fallen god-king in divine war. But he was cursed by the god and lost all his emotions. Until finally he created the reincarnation magic of his skill to remove the curse.

900 years later it has passed and ken successfully reincarnated. Unfortunately, The curse cannot be eliminated. And ken must be forced to live his life without his emotions. Ken finally Determined to live a quiet and peaceful life in those days as a….Butler?

An RPG gamer who played the realistic VRMMORPG ‘The Amber Sword’ for years, finds himself teleported to a parallel world that resembled the game greatly. He takes on the body of an NPC who was fated to die, and with the feelings of the dying NPC and his own heartrending events in the game, he sets out to change the fate of a kingdom that was doomed to tragedy.

- Description from novelupdates

The leader of the thousand demons, the Demon God Chun YeoWoon. Due to an unfortunate accident, he had been sent to the distant future.