I guess I can't find a flaw in this outstanding manga.

While the first few pages are not very attractive, the later part of chapter one gives me a reason to read until the end.

Story is dark, and how the story is delivered itself is not light at all. As far as I read, I only can breath before the later part of chapter one until the end. Even though it's dark, I appreciate how the mangaka could deliver the story without having me had to withdraw from keep reading (from overly dark and frustating).

Art and character likewise is very great. Aikawa as the main lead is very well-drawn for me. The other characters also nicely done too.

For enjoyment, as I wrote before I couldn't take a breath to keep me from reading. The story is delivered really fast and eventful. It's very enjoyable if you read this with concentration, not as a time-passing by.

So, overally I really impressed with this manga. Nice background story, story development and delivery, great art and characters are what keeps me reading.