Master Keaton is by the same artist as Monster, though he didn't do the story on that one. Not identical, but it's got an episodic detective thing going that might fit in with what you're looking for.
Kemonozume is a very well paced show. If you can get past the artstyle it's definitely worth checking out.
If you're looking for something dark, both Akagi and Kaiji (by the same author) are worth taking a look at. Akagi unfortunately ends on a cliffhanger, but it's one of my favorite shows ever, and I really don't even know how to play mahjong.