looking for a manga I read once

Hello, could you help me find this manga please?

It's a story that begins in high school then goes on in adult life. About 2 guys. Once is a cop undercover (kuze?)
The other is up to no good. They say: why is it you?
He reeks of corruption. The black guy used to get blackmailing material on everybody at school, just to get the upper hand.
Once adult, he gives false thread to the cop cause he knows who he is.
Can t find this manga, it's crushing me!!!
Thanks for help ;)