Seonghwa is an Incubus.. the corresponding spirit in female form is called a succubus. He was the strongest of his kind and the ruler of them all

He was searching for someone new... Someone who he could feed on. As he searched, perched ln top of a tall building, he saw a male this time.. You, Hongjoong.

He flew down closer to get a better look and decided this guy was perfect.. Hongjoong was now his prey..