In my childhood, like 10 years ago I watched an anime, not a series I think, it was a movie. All I can remember that it was very disturbing.
I remember some details like there was a virus or something and one city in Japan started a riot. One of the most memorable scenes was when the main character started to beat the crap out of a riot policeman, there was a lot of blood and swearing, and one girl ran to the boy to stop him.
Also in the end one man or the main character started to transform in to some big disgusting mess and got bigger and bigger and one blue serum saved him. I was trying to find that anime since then but I can't find it.
I want to see that now where I am mature enough. It is not "Vexille" like one of the most suggested