Responses
So, I'm guessing it's literal after rereading. His hatred of humans literally dyed his skin black. I don't think the crest has anything to do with it. Again, BAD subtext.
https://www.mangago.zone/read-manga/noroware_hime_wa_bougyaku_na_kishi_ni_metorareru_ai_no_shirushi_o_okufukaku_ni_kizami_tsukete/uu/to_chapter-1/pg-16/
He dyed his skin black??????