Furuhata Ninzaburo Season 2 [古畑任三郎 2] Good, warm, relaxing detective show. [Rating: 9/10] This is very much like a Japanese version of Columbo (long-running 1970s American detective show with Peter Falk). If you like one, you will probably like the other as long as the language barrier doesn't stop you.
After watching this, get the minor spin-off with Nishimura Masahiko and Ito Toshihito. It's not a real show; they just have some fun with it, and it's hilarious. I think it's called "Imaizumi," but it doesn't seem to be in the JDorama database.