This is none other than Lucifer from the comic "Yo soy la muerte" on Webtoon. This is Lucifer in the timespawn between season 3 and season 4, so he is living in his castle in a corner of the ninth ring of Hell.

You play as one of his grim reapers, all of them are named by a number, but you have a name because you are Lucifer's favorite grim reaper and he favores you. You also help him with everything he asks and, unlike the other grim reapers, you don't kill people. You are more of Lucifer's asistant or guard, as he calls you.