This series is really good and in my opinion it doesn't get enough recognition.  I don't know much about the manga, except that there is one, and I believe it has been released in English, too.  The show was originally a four part OAV, and then there was a TV series.  I'll probably deal more with the TV series.  There was also a spinoff called Vampire Princess Yui, but I don't know a whole lot about that either.  The show can be kind of dark at times, but it's not bad.

    Miyu is the Guardian, a vampire who is frozen in time with the job of catching stray Shinma (demons) and sending them back to the Dark (I guess it's kinda like hell, except that they escape sometimes).  Miyu was frozen at age 13, so she never ages physically beyond that.  She goes to different schools until she settles at a certain girls' school, pretending to be a normal junior high student while looking for clues concerning her quest.  She is helped by Larva (total bishounen under that mask!) and Shiina.  Larva is a Western Shinma who was supposed to kill Miyu, but couldn't and so his bite awoke her vampire nature and now he is her servant.  He wears a mask and a black cloak.  In the OAV, he can't remove the mask or speak, but in the TV and manga he can do both.  Shiina is a small Shinma that looks kind of like a rabbit, with one ear flopping forward and one flopping back.  The eye that is covered by the ear is really freaky and big, but I guess Shiina can sense stuff with it that a normal eye can't.  Miyu is not a typical vampire.  She has a reflection, she can go out in the sunlight (how else would she go to school) and she doesn't kill people.  If she takes someone's blood it gives the person eternal life in a kind of dream state where they are happy.  She only takes a person's blood if their life is not worth living anymore.  The reason that Miyu is being the guardian is because she is trying to save her parents, who are also frozen in time.  They will all remain that way until the last Shinma is sent back to the dark, then theoretically Miyu and Larva will follow.

    There aren't very many fanfics available for this series unfortunately, mostly because the majority of the links are pretty old and defunct.  But I know where to find a lot of the available fics, and I will be happy to share my knowledge with everyone.

I have this picture as my background!

Picture from:   Vampire Princess Miyu Image Gallery