I like it. It isn't as good as Berserk, but I like the action and the morally grey characters. Basically, the main character was a good guy who got fucked unfairly, and is out for revenge despite being conscious of it being a pretty bad idea all around; and the main antagonist is a guy who fucked someone over this one time but has basically done nothing but good ever since. Made me think who to root for a couple times, although it also does get pretty black & white some other times. It does have quite a few boobies around, but as a long time manga reader I've learned to look past/ignore it and I don't find it a big deal.

Basically, not the best manga ever, but still a nice read.

That's a better impression than the few reviews I've read were able to give. Thank you.

Sounds interesting, I'll probably pick up 0 sometime soon. It does start at 0, right? Amazon gives that impression.

It's a matter of taste, I guess. I tend to like this kind of stories so I'll have a forgiving bias towards it. I do heartily recommend Shin Angyo Onshi too, since you haven't mentioned it and I think it's a very good one.

As for the question, can't say for sure. I hardly ever buy manga and just download scanlations, so I'm not sure how it's organized, but I think it did have some kind of prologue volume to begin with (and yes, you should begin reading from it).

Thanks again. Saw the movie version of Shin Angyo Onshi and liked it a good bit. And by better I meant more comprehensive, most people said, "Better than dirt, not as good as Berserk."