Blood Alone

Former vampire hunter Kuroe Kurose is leading a very different life these days; despite vampires having killed his Hunter sister and accidentally granting him immunity to their glamour; he happened upon a young girl named Misaki who had been freshly turned into a vampire. Settling down and becoming a novelist and Private Investigator, he has adopted her and is trying to help her from succumbing to the Enemy Within.

Tropes used in Blood Alone include:

And I Must Scream: The body-snatcher is immobilized by being turned into a vampire with a permanent broken neck; then left in an abandoned basement.
Awesome McCoolname: ...seriously, Kuroe Kurose? ("Kuro" means "black".) That's like naming someone Darke McDark. It is revealed to be a name he was "allowed" to take by his teacher.
Badass and Child Duo: Kuroe, a badass Vampire Hunter who has taken in tween Misaki, an unawakened vampire girl whose vampire hunter parents were killed by vampires who then turned her into one.
Body Surf: Early on Kuroe and Misaki face a human who can steal bodies of those near him when he dies.
Brother-Sister Incest: Kuroe wasn't quite to this level with his sister, but it was close.
Child Soldiers: Maria, who was trained by vampires to be an assassin.
Mr. Fanservice: Kuroe "Tall dark and bishy" Kurose. Also Higure in a Shotacon kind of way. Blood Alone is technically a Seinen manga but may actually have a higher female than male readership.
Failure Knight: Kuroe is haunted by his failure to save his sister from vampires; Misaki reminds him very much of her.
Friendly Neighborhood Vampires: Misaki's "vampire self" hasn't even awoken yet, Sly was changed by Orphans (those without a clan) so hates them and helps Kuroe out, and while it's likely that Higure has Offstage Villainy; he has been nothing but helpful to Misaki.
Gender Blender Name: Kuroe's name is actually a romanization of 'Chloe', because he's inherited the powers of Chloe the magician.
Gay Vampire: Higure is rather fond of his Bishounen Renfields; nothing outright is stated; but he does like having them snuggle him. He also enjoys hitting on Kuroe; and while his being a vampire elder means he's dangerous, his being gay isn't demonized.
Heroic RROD: Misaki's Enemy Within surfacing a lot quicker the closer to true death she is. It (her vampire side) warns Kuroe of this after she nearly killed by a body snatching murderer.
The Hunter: Kuroe's old profession, these days he's more on the True Neutral path, since having a peaceful co-existence with the local Vampire Elder is beneficial for Misaki.
Legal Jailbait: The implied future for Misaki, played for gentle angst. She has a crush on Kuroe but knows it will never go anywhere because as an unaging vampire she'll never become an adult woman.
The Obi-Wan: Kuroe was taught to be a Kung Fu Wizard by his Sensei; a mage dressed in a Victorian London style Black Funeral Gown who can Stealth Hi Bye, and was apparently named Chloe. He refers to her as "The Lady" and other vampires call her "Sinistre Femme" or "The Woman With A Forbidden Name"
- Doubles as Sexy Mentor. Just see the beginning of Volume 6.
Older Than They Look: Naturally, when dealing with vampires, but Higure the local Vampire Elder looks like a child the same age as Misaki.
Our Vampires Are Different: ...but apparently not that different. They are remarkably like the ones from Vampire: The Masquerade. Sunshine is actually a weakness, surprisingly. It is commented that they're mostly imported from Europe. One major difference is that it takes a while for the Enemy Within to kick in; it's accelerated should a vampire get injured.
Reluctant Monster: Misaki is a complete innocent.
The Renfield: They are actually called "Renfields", servants to vampires who are given vampire blood. This generates a feeling of love and obedience.
- Maria gets adopted by Higure, and he's a perfect gentleman who simply tells her that she's now part of the family. He doesn't attempt to control her will at all. Of course, she's not really his taste...
Supernatural Martial Arts: Kuroe and his sister know a form of "magic martial arts" that let's them fight vampires.
Undead Child: Both Higure and Misaki so far have been friendly; Higure is competent; but he reveals that ultimately all undead turn into monsters. It's just a question of how many centuries it takes.
Vampire Detective Series: It's not Kuroe who is the vampire, but it's definitely the genre.