Down-on-his-luck Siyun is prone to fainting and has a mountain of bills to pay. When he wins the "Vampire Lottery," he gets matched with a vampire named Jinu and becomes his blood donor. The two of them move in together, and although their relationship is strictly contractual, Siyun and Jinu soon begin to fall in love. Things are finally looking up for Siyun--until his rare blood type starts drawing the attention of other vampires…