GTO, Saikyou Densetsu Kurosawa Recommendations
The main character wants to improve his life. Some days are good, others are horrible and are hilarious. Mr. Kurosawa is sort of a "what if" older version of Eikichi Onizuka. Both men are extremely tough and the type of character you want to root for. The main turning point in both manga is that the main character has to deal with some troublesome middle school students. Sometimes it's frustrating to see the main character get punished but there are many rewarding chapters too. If you like a manga with drama, comedy and a meaningful message you won't be disappointed.
I'm a fan of GTO and Onizuka, and this manga and especially Kurosawa's attitude against bullying and giving people hope, is very similar to Onizuka.