You Can't Have My Blood

Down-on-his-luck Si-Yun 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 Jin-U and becomes his blood donor. The two of them move in together, and although their relationship is strictly contractual, Si-Yun and Jin-U soon begin to fall in love. Things are finally looking up for Si-Yun--until his rare blood type starts drawing the attention of other vampires…

(Source: Tapas)

Note: Includes three extra chapters.