A 14-year-old 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, Kojou 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 suck her blood in order for him to gain control over his familiars. Unknown 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. Yukina is afraid of flying as shown in episode 10 with Kojou noting that Nagisa also have the same fear. Yukina often get irritated by Kojou when he somehow mention something like being with her sucks that makes Yukina upset without noticing her feelings for him. For instance in episode 10 when they were trapped on an island, he mentioned that staying there with Yukina for the rest of their lives would suck a lot angering Yukina as he just blurted out things without thinking of her feelings. Yukina is showned by the end of the first arc, she seems to have developed feelings for Kojou. She offered her blood many times to Kojou even to resurrect him when he was pierced by Kanon as was shown in episode 12. She does not hesitate at all when it comes to Kojou showing multiple times that she does love him a lot. In episode 19 she even told him to stay by her side forever as she is always worried when Kujou is up to something stupid and risk his own life for others. In Strike the Blood EX, she is presumed to be married with Kojou and they have a daughter named Reina.