It's no secret to anyone that Ayaka drinks, but you know it's bad when even an anemic vampire refused to take her blood, when she offered it!
Ayaka: (suggestively) "Weel~elll, I can offer you a few cc's, if you like." *wink!*
*lifts her hair, exposing her neck*
Bosco: (clears throat, looks away) "I'm uh... afraid that won't do."
- It looks funnier out of context, but Bosco explained earlier that, when it comes to blood, vampires have tough dietary restrictions. And to be fair, he's controlling his blood lust to the best of his ability. He only burdens his girlfriend four times a year, and only for 200cc's at a time (less than a transfusion unit).
Bosco: "You can't imagine how difficult it is to find someone of this kind in a modern city like Tokyo. A girl who's a virgin, doesn't drink or smoke or do drugs? Why it's almost impossible!"