Looking for a psychological manga about school life of a boy who goes to the same secondar...

Looking for a psychological manga about school life of a boy who goes to the same secondary school his brother attended before the brother committed suicide. He wants to find out the reason for his brothers suicide and also the brother used to rape him when he was little. When he is at the school he finds out his brother was a whore and that the school students run a system of gangsters and rape and violence that is keeper under cover. He gets sucked into it’s well and is raped and goes through the same experience as his brother. The manga is generally very Violent and severely hard core and kind of brutal. But it’s interesting. It’s been a while since I read it so my memory of the plot might be foggy but if you can pick up on any details please let me know. (●'◡'●)ﾉ