Lament of the Lamb, Volume 3

There are no special powers, no kid discovering these "powers", no mecha, no slapstick comedy, no chibi, just straight up story-telling with a dark/sketchy (resembling of Hiroaki Samura's style of Blade of the Immortal fame) art style, dealing with a depressing issue, but not gothic just to be gothic. When I read the first volume and up to three, I thought "Why do they have a Parental Guidance issued out?", barely any bad language, no nudity, no violence (unless you consider blooddrinking violent). Here's a spoiler however... I've read volumes 1-3 of Angel Sanctuary and saw the anime.... there's a hint of why there's Parental Guidance. Pretty much the subject matter is very deep into seeing depression and how the logic of depressed people think. "If I told my friend's my problems, and involve them, will it make a difference other then worry them? Why bother, no one can help my circumstance?" This is the main thought processes of Kazuna and Chizuna, being the only ones to help each other.