I wouldn't be at all surprised if the labyrinth has something to do with the food supplies too. If it's based on some sort of multifloor dungeon crawl like I think it was suggested, who knows what's in there. Monsters for meat, monsters for vegetables? Dungeon Meshi this bitch up. Otherwise I suppose they'd just have to be an important trade hub. Foreign foods come in, local monster drops go out.Where does that huge city get its food? Fishing is obviously a part of it since it's next to a sea, but otherwise everything outside of the walls seems like wastelands and rough, rocky mountains.