I would strongly recommend the Soulless Manga by REM based off Gail Carriager's books.
I re-read them this week and they're as good as I remember.
It's a fantastic adaption, absolutely fantastic artwork, really well adapted from the source.
Basic story, in a Steampunk-era Britian Alexa Tarabotti is a soulless, born with the ability to cancel out supernatural abilities.
When vampires and werewolves across the UK start being abducted and disappearing she is recruited to help Lord Maccon, werewolf, Scotsman and head of queen Victoria's supernatural bureau (and obvious crush) to investigate
It has pretty much everything an adult reader could want. Funny, appropriate violence, vampires, werewolves, libraries, suggestive nudity, airships, yuri couples, yaoi couples, straight couples, spies, plots, villains and proper British etiquette... great artwork.
Also comes in three volumes. Go buy it from all good stockists.