ریوکا سواین

A female vampire popular with the Day Class students and is one of those are the most faithful and protective of Kaname. She seems to dislike Zero because Kaname acknowledges him and carries bitterness for Yuuki's place in Kaname's heart as her feelings for Kaname run deep. When Yuuki was younger and had not become one of the school's Guardians yet, she once witnessed Kaname drinking Ruka's blood when she paid Kaname a visit. Ruka has feelings for Kaname, although he does not reciprocate them and only drank her blood one time to keep himself from biting Yuuki.

[Spoiler: In chapter 81 it is revealed that she has the ability to create illusions.]