My absolute favorite jdrama for relationships between women is BOSS, for reasons that I go on about at length [spoilers in the second half]. It's a capery cop show, basically, whose characters make it amazing. Short answer: women as friends, mentors, and rivals, on the same show, sometimes with the same women. The romance on the show is a nice characterization sidenote that holds far less weight (for both story and character) than the lead woman's career, there are interesting female criminals (as well as male ones), and the women on the team (leader, forensic specialist/investigator-in-training, and lead forensic specialist) have the greatest narrative weight.

The second series currently airing seems to be jumping the shark, but the first one is awesome.