Hitsuji no Uta

The members of the Takashiro family share a terrible curse -- they have a thirst that only human blood can slake. Sent away after the death of this mother, Kuzuna Takashiro has long been blissfully unaware of his 'condition.' When Kazuna's teenage hormones begin to rage, his uncontrollable bloodlust suddenly rears its head ... (Source: Tokyopop)