 If you liked
Epitaph
|
 ...then you might like
Diabolic Garden
|
Two stories immersed in the purest Gothic atmosphere.
The overall mood is indeed relatively dark, and addresses themes like death or in the case of Diabolic Garden, demons. However, they still have their funny moments.
The dress style of the characters is also similar. Both authors propose girls in gothic lolita. If you like this style of characters, you'll be happy with both Epitaph and Diabolic Garden, as both manga feature a lot of them.