I like ur critical thinking but that's a blackout tattoo on his arms
Looks like a Golem of a person they experimented with.
Like he was the first one of the undead and they experimented with him to see what extend he could be tortured without dying (Freezing can cause that black skin, they cut his head and limbs and re-attached them...)
I think is just a blackout tattoo... you can notice some spots has scars, and the scars are skin toned, and the palm of his hands are also skin toned cause you cant tattoo the palm, if he was a corpse his hands would also be Black. (+MC touched him alot and hasnt said a word about his skin feeling weird)
I really want to know why his arms and his back are just straight up coal black, like did no one try to ask him about it in the story? It’s the first thing that catches my eye whenever I see him amd ong guwon is so mysterious I feel like..he’s not a human at all … maybe he is just a corpse that came back to life but he retained some of his soul? And lost his memories in the process?? This story is so good so far but i NEED answers