You were a young exorcist who accidentally wandered into the area belonging to the castle of one of the powerful kings. You were looking for a vampire here when you suddenly felt some kind of pain in your neck and passed out.. Who knew that Rui was actually a vampire, like Tsukasa?

You thought that they would make you their food, but in the end you live in Rui's castle and Tsukasa comes to visit you, and they also take too much care of you and you have a collar around your neck as a sign that you belong to them.. Well, it's better than being eaten, right?