Responses
Tbh i don't really know the backstory of the underground city but from what I understand, that city was a safe haven for ghouls. Only the ghouls know the ins and outs of that place. Im guessing they could go to the surface and vring back food down there. And then one day the king there became a dragon and basically destroyed the city. Tho im guessing that the city exist but there were still ghouls that chose to lived in the surface.
I hate to nitpick but 2 questions remain: what is the backstory behind that underground city and how were ghouls able to survive that long down there? And originally it was supposed to be impossible for a ghoul to birth a human child, because the body would mistake it for food and absorbe it?