Millions of years ago supernatural beings lived on Earth and controlled society through their power but a group of hunters led in the shadow of plans to exterminate them so that the population could regain their place in society.
After decades of hunting them down, the hunters managed to kill them all, and life resumed without its supernatural beings called "vampires" , they drank the blood of poor human beings and left in dark alleys between life and death so it was their turn to taste death.
But figured that vampires created children or cases in which they came to die, they took them away from Seoul so that they would grow up in peace and safety there are about 20 vampires, but no human even knew the hunters so line them continue to the greatest distress of humans.
The children of vampires have returned to Seoul and this is mingling with the population and acting as humans but factors in their own lives will put them and as well as the lives of people who rub shoulders.