After the advent of the deep-sea era, the wise races that survived the old world and established City-State civilizations were not limited to humanity—apart from humans, there were the Gyplo People, Senkin People, and Elves, three races that existed in this world, each developing their own civilizations.
This was knowledge written in Nina's textbooks, which Duncan already knew, and he had been greatly interested in these "different races" mentioned in the textbooks, especially the Elves—a race that always appeared in all kinds of fantasy stories, surrounded by a mysterious aura, actually existed in this world, which at one point fueled his curiosity immensely.
The illustrations in Nina's textbooks had once depicted the physical characteristics of the Elves to Duncan: like the Elves of his imagination, they had long pointed ears, slender bodies, and beautiful features, so beautiful that it was hard to distinguish male from female.