 If you liked
Epitaph
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 ...then you might like
Sister Blood: Gensou no Tsuki to Furueru Chi
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A similar atmosphere. Both share a pure gothic atmosphere. Death is their common theme: in the case of Sister Blood, it's because one of the characters is a dangerous vampire, and in Epitaph it's because the two protagonists work for a funeral.
The main characters are also similar: in both cases, there's a duet. Both are portraying orphans. In each duet, one of them has a more or less close connection with the supernatural. There is also a lot of romantic innuendo between the two characters.