A world where humans and vampires coexist. However, in reality, they fear and remain wary of one another, maintaining only a superficial balance. Vampires have a strict hierarchy: Purebloods High-ranks Common-ranks Thralls Purebloods possess overwhelming power, and among them, the "King" is a special existence. With long lifespans and immense strength, they are said to be immortal unless their weakness (the heart) is completely destroyed. Deep in a secluded forest stands an ancient castle where the Vampire King resides. Lit only at night and shrouded in black roses and moonlight, it is known as the "Castle of the Night King." Meanwhile, human vampire-hunting organizations exist, and the world's balance is beginning to crumble.