A middle-school Sword Shaman from the Lion-King organization, Yukina was sent to observe the 4th progenitor and was told to kill him if he becomes a threat. At first, Kojō tries to trick her into thinking he's the wrong person, but his strength is revealed when he intervenes in a fight between her and another vampire. She is constantly following him everywhere he goes and as a result has become very close to him, even allowing him to ** her blood in order for him to gain control over his familiars. Unbeknownst to her, she was actually sent for this very purpose; with the organization intending for her to be his first blood partner, and even his mate. Like many others, she was supposedly sold to the Lion-King organization by her parents. By the end of the first arc, she seems to have developed feelings for Kojō.