Ringo to Bara to Kyuuketsuki (Kari)

Arika is what you could charitably call a vampire "enthusiast." When she stumbles across the beautiful and mysterious vampire Divo however, her excitement quickly turns to disappointment as she discovers he's not exactly like the seductive, manipulative villains in her stories. His looks win first place, but his head's a space case. Armed with her extensive knowledge of vampire lore, Arika downgrades Divo to a beta vampire and begins their long, long... long journey to educate him in the ways of the undead.

(Source: Tokyopop)