Selene and Kurama
"Your Earth is not mine," Kurama confirmed. "If there were such a clan, I would know it. One learns a great deal over the course of two thousand years. Quite frankly, the existance of someone of your nature would have thrown Reikai into chaos. They would have tried to conceal it, but they're not terribly good at secrecy. Makai's lords would have found out, or some foolish human intent upon turning your people's nature to their own uses." In spite of Yuusuke's efforts to change Makai, the balance of the three worlds was still precarious.
"I admit, I miss that world, despite the novelty of this one."