Directed by Seijun Suzuki
Written by Ichirô Ikeda and Tadaaki Yamazaki
AKA: Youth of the Beast
IMDB

An ex-cop is recruited by a gang, only to make a deal with a rival gang. This sparks a gang war.
Okay, the plot synopsis is lacking because I missed enough of this movie to be confused, but understand it mostly while I was watching it. I also don't want to ruin any of the twists.
I loved this film. The jazzy score is fantastic. The cinematography is fantastic. It's just a really well made film, especially for an action/film noir movie. It's a very technically arty movie, yet is accessible to anybody who doesn't mind the violence.
I'm going to try and watching this movie again so I can write a better review.

10/10