It focuses on a naive, loudmouthed teenager named Rion, who investigates a host club full of vampires when she suspects they must be related to the disappearance of a lot of people in the neighborhood, including her best friend. In the process she begins to befriend them, especially the leader Suou, with whom she develops a romantic relationship. Ultimately, she figures out the vampires are not the cause of the disappearances, but her adventures with the vampires are only beginning.