Shizuka Hio is the pureblood vampire who bit Zero; even her fellow vampires are uneasy around her and refer to her as the "Madly Blooming Princess". A manservant whom she loved (a former human vampire, falsely classified by the Hunter's Association as Level E) was assigned to be killed by a Kiryu vampire hunter. Enraged and vengeful, she attacked the Kiryu family, killed Zero and Ichiru's parents, turned Zero into a vampire, and took Zero's twin, Ichiru, in as a devoted servant. She was originally Rido Kuran's fiancée, but they never married due to his disappearance and finally her death.
Because Shizuka's blood can prevent Zero from falling to Level E, Yuki risks her life for Zero to be able to drink Shizuka's blood. However, to protect Yuki, Kaname kills Shizuka and drinks her blood, leaving only a small amount for Zero to drink. Unfortunately the blood is drunk by Ichiru, who arrived to find Shizuka first. Before dying, Shizuka warns Kaname that he will live in darkness and has summoned a sinister future for himself.