I don't intend to write a very long review since I don't like to and I don't like to read long ones so...
You all know what this is about there's the synopsis.
The story I gave it an 8
Art a 7, nice fights, nice blood yet character designs felt a little insipid.
Sound (for me) was great like the soundtracks they used.
Character this one is kind of a problem, because characters are not very well developed but meh, they are fine in the long run do not interfere with useless stories.
Enjoyment was an 8 although I will say something about my enjoyment with the last ep.
Overall it was a good anime, great to watch some gore stuff and some nice, deep, dark story.
Now my only regret with this first season is that the MC is a plain idiot, who's not strong and pretty much it does nothing but whine in this first season (second is another story), but really in the anime the last episode (12), for me is the worst episode I've seen in an anime from this magnitude. It is boring as s*** nothing really happens, it is a waste of 23 minutes all the things they talked could've been done in 3 or 7 minutes, but the other is just a pointless conversation which follows to a cliffhanger. I gave it an 8 because of the start of the series and its mid-point, but I almost drop this anime because of the 12th episode.
