I purchased this manga on a whim, but after reading the first volume I was straight back to the store buying the rest.

There is a hell of a lot of smut in this, no denying that, but the story is also strong. Sister Erna meets a vampire who is supposed to be a heartless beast, which she initially thinks he is, but she comes to believe she can make a better person of him so allows him to steal her away from the church.
Her mission to make him a better person obviously doesn't go so swimmingly, but over the course of the four volumes she begins to succeed little by little and the two of them grow closer together and overcome the obstacles they face as a vampire-human couple.

I really enjoyed it - devoured the whole series in one go. I would have liked to read at least another volume, as it felt like the mangaka left me hanging on some things, but I've discovered there's a sequel so now it's my mission to find the sequel in the shops too...
Hope this gets translated for other readers soon.