A race different from humans that lives on the Earth, called by the name "Another".
They usually live among humans, with the appearance of normal humans so most people don't know about them, but they are all over the world. They exists in many countries, and in Kore they appear as Dokkaebi and ghosts.
Ordinary humans can't see their appearance until they reveal it on purpose. However there are people with special powers, and some of those powers allows them to see the real appearance of "Another".
People with powers are preys for Anothers. Depending on the size of power, it becomes a good nourishment for them. The series protagonist, Han Yu-Hwa is a constant target by Anothers because of his abilities.