I read it years ago but I was obliged to leave a review as it is definitely my favorite novel.

The anime doesn’t do it justice, so they do want to know more about No.6, it would be good to read the novel.

History: This is a post-apocalyptic world where Shion and Nezumi unravel the secrets hidden in the city. Under this premise develops a great science fiction story, even if you are not a fan of this genre I can assure you that you fall deeply in love with everything.

Characters: The characters are really endearing, each with a very outstanding personality, most have an incredible development.
I would like to make special mention to Shion and Nezumi as they both share a very special bond; each interaction is a heart attack. You get to love them too much.

Enjoy: Since you start to read it, it gets you hooked in a great way, so if you’re even busy, you find yourself reading it every time you have some free time. The enjoyment is great.

General: As in everything, there are moments with which I do not agree (especially going towards the end) but it is minimal in contrast to the whole work in its entirety.

History: 10.
Characters: 10.
Enjoyment: 10.
General: 10.

Please encourage yourself to read NO.6! you will not regret ^^