iza u saw no.6 right? whats it about?
Yes!! It's one of my favourite animes.
Essentially, there's this "perfect city" known as No. 6. It's set up to be an utopia, every person has a place and a role to perform and all that jazz. The main character, Shion, lives in this city. He's something of a child prodigy, and because of his intelligence he was essentially set for life; the city had him and his mother moved into the nicest area of town and he's being prepared to get sent off to the Special Curriculum. He wants for nothing.
...Until one day a boy from outside the city shows up. This boy's a wanted fugitive, and even knowing that, Shion offers him shelter in the midst of a storm. He's found out, and Shion is stripped of his privileges and sent to the "poor area" of the city to live in.
Fast-forward four years. A series of strange deaths take place within the city (exceptionally odd, considering this place is "perfect" and healthcare is readily available), all attributed to "death of old age". Poor Shion ends up finding a body and witnesses what's actually happening to these people, and everything just goes downhill from there.
He ends up wanted for murder by the government, despite having had nothing to do with the deaths, and who shows up to help him but the boy he gave refuge to so many years ago? Shion leaves the city with him, and slowly starts to piece together the fact that this "utopia" isn't all that it seems.
I know that's a bit of a roundabout summary, but I don't want to give away too much. I really highly recommend giving it a watch, though! It's an incredible story!