Demon's Requiem

A middle-aged man who lived as an evil narcissist—dying out in the snow without regret. But it seems death was not his end. He awakens in the frail body of an enslaved boy named Lainus, collared and caged in a world ruled by beings called Mystics — where he slowly begins to understand the world around him, manipulating, killing, and stealing for his own benefit and twisted amusement as he grows ever stronger — dominating without any grand goal, simply acting because he can and it gave his life a small meaning and thrill