Have you read Kamisama ga uso o tsuko?
Aku no Hana is another coming of age type of story as well.
Are you looking for manga with plot similarities, or similar in its somewhat vague artsy direction and style?
As far as anime gore goes, I'm not to familiar with it.
Have you seen the basics:
Berserk
Higurashi no naku koro ni
Elfen Lied
Hellsing/Hellsing Ultimate
There are also series like
Claymore
Deadman Wonderland
Attack on Titan
That one anime where a guy had to fight a grizzly bear in a cage match for some reason
Terror for Mars
Bokusatsu Tenchi Dokuro-chan
Btooom
Blood (the last vampire, +, -c)
I think even stuff like Corpse Party may have an anime ova now.
There are a ton of series that contain gore, but is it important to have it be a central focus?
Either way this list should hopefully get you started.
