Lovephobia Volume 1 by Natsume Kokoro

* Ako stumbles into her parents' murder scene while the killer still lingers over them ― a vampire named KOH! He turns his attack on her and viciously drains her life, but even as she dies, her terror and revulsion turn to... pleasure? Now, Ako has joined the ranks of the undead, feasting upon humans at her master's command, but what will become of her only living brother? The poor boy still awaits his sister's return, never knowing that another vampire hunts him from the shadows.