Go and dive into the wonderful world of Gokusen. It's exactly what I think you are looking for and on top of it there are a lot of them! It has the delinquent box checked, also it has inspiring moments and good comedy, no romance at all. I really recommend this drama (and all the following seasons and movies), so give it a try.
There is also Dragon Zakura, it follows the same pattern and it's really a joy to watch!
