A 14-year-old selfish but adorable vampire, Hazuki was separated from her mother and restrained in a castle in Germany. She escapes the castle with Kouhei's help and flees to Japan in search of her mother.
A vampire's "kiss", the act of drawing blood from a mortal, normally turns the mortal into the feeding vampire's unwilling servant, but Hazuki's attempt on Kouhei fails. According to the storyline, Kouhei is narrated as the "Vampire Lover", and therefore is immune to the binding power of Hazuki's vampiric "kiss".
Despite her continuous claims that Kouhei is her slave and must obey her every command, Kouhei refuses to do so. Her family is desperate to retrieve her because she is actually a "daywalker", a vampire who, unlike others of her kind, can withstand sunlight. She is plagued by an alternate personality named "Luna" that was forced upon her by her vampire relatives to keep her under control.