It's tricky to recommend jdramas 'for guys' - there are different demographics and genres, so it really depends on the individual. Having said that, I watch a ton of the stuff (I'm not an anime fan; dramas and variety shows are the only Japanese TV I watch), so maybe I can add a few options that are not obviously skewed toward a female audience:
Gokusen: Yakuza heiress follows her dream and becomes a maths/homeroom teacher to Shirokin Gakuen's class 3-D - students on the verge of failing or getting expelled for disciplinary problems. Imagine
Dangerous Minds converted into a comedy. I only like Season 1 (everything after that felt like a rehash), but there's also Season 2, Season 3 and a movie, which gives you thirty-something episodes to play with.
Maou: Remake of a kdrama. Seemingly kind-hearted lawyer secretly plots revenge against his brother's killers; detective with a dark past investigates a a mysterious series of murders.
Ryusei no Kizuna: Three siblings make a pact to avenge their parents' murder. Somehow manages to be both dramatic and comedic by turns.
ROOKIES: Baseball-centric drama of the hopeless-sports-team-pulls-together-under-a-new-coach's-guidance style. As an Aussie (and hence raised on cricket rather than baseball) I found it a bit dull, but US jdrama viewers seem to like it...?
The Quiz Show 2: Contestants are invited onto a 10-question quiz show modelled on Who Wants To Be A Millionaire. Eight correct answers and they get a wish granted by the TV network, ten correct and they win 10 million yen. The catch: the contestants' lives have been researched in advance, and questions eventually delve into past crimes, which they have to admit to in order to win. There's also a side story regarding the relationship (er, not romantic) between mysterious host and the director. I've never seen the original, but Season 2 was engaging.
Bambino!: Novice chef from Fukuoka with an ego problem gets a traineeship in a top Italian restaurant in Tokyo, realises he's not as good as he thought he was, gets smacked down a lot, learns how to become a real chef. I ended up having to watch this drama after dinner, otherwise I found myself compelled to head for the fridge within fifteen minutes : /
Also agree on previous recs for
Liar Game,
My Boss My Hero and
Bloody Monday. LG has two seasons and a movie, BM has two seasons, so 20+ eps to work with.
I could probably come up with a dozen more if I had my back catalogue in front of me, but I'm not home at the moment... Hopefully this will give you a few shows to work with, though