"Chu♥Chu♥Chu" or "C♥C♥C" (Kiss Kiss Kiss) Tsubaki Nakashima 2 volumes-complete
Honey is a middle school student who's always passed up as elementary kid. Then she meets vampire Robin who transforms her to an adult every now and then. This would have been under the previous post (for almost a year now) but as I've read the recent chapters the second and third guy have entered into the spotlight. The story is a mixture of Bisco Hatori's "Millenium Snow" and Matsuri Hino's "Meru Puri" with silly smuttiness. Next thing you know someone will create a manga that has "Ouran" meets "Vampire Knight" plot. LOL.