Vampire Hunter D: Bloodlust

Charlotte, a young woman, is abducted by Baron Meier Link, a vampire nobleman who is known not to harm humans needlessly. Charlotte's father, Elbourne, hires D, a dhampir, to find her and rescue her, and alternatively, kill her humanely if she's been turned into a vampire. He offers D $500,000 as a down payment, and offers him $10,000,000 if he carries out the job. D has Elbourne double the payment, and agrees to search for Charlotte. Read more on Wikipedia.