I've been re-reading most of his works recently, though they have a good deal of problems; ranging from using his characters as mouth pieces where it kills the flow of the story to non-deliberate misogynism that's in a lot of male mangaka works. The only difference is instead of slim busty women all going after one man, his women are somewhat normal, no bustyness or harem bullshit but he puts women in horrible positions where he tries to explore some ramifications of the position he's put them in but fails and comes off misogynist even though he's not trying to be. Then there's his darkness, where at times it comes off as trying to hard to be dark. He's putting his characters in this horrible positions to keep level of tragedy and darkness ever present; well that's how it feels. Even with all his problems, his mangas are worth reading because they take you to place most manga or comics won't even touch.
I recommend checking out Owari to Hajimari no Miles, Nanika Mochigatte Masuka & Bokurano from Kitoh.
Another mangaka I've been re-reading is Natsume Ono. Man, I fucking love Ono's work.
She has an amazing grasp on writing characters. They're layered, nuanced, complex and with each page we learn more and more about them; there's always more than meets the eye with her characters. Not only is she a great character writer, her plots are rather intricate too. Actually, she's a great magaka. She knows how to pace her story, keep it moving while allowing her characters space to breathe, move and become than cardboard cliches that just move the plot. One of the best examples of this is Ristorante Paradiso, which tells a tale of a mother/daughter reunion in a little restaurant in Rome. A simple premise that takes some complex turns and becomes more than what it seems.
Another favorite of mine and her most famous work is House of Five Leaves. It follows a hungry, desperate ronin named Akitsu Masanosuke who is skilled but has a diffident nature; having such personality does not vibe well with the lord he's employed under and he gets fired. Through some wanderings, he find Yaichi, a very charismatic leader of a group called Five Leaves, a gang. He becomes Yaichi's bodyguard and though the activities and beliefs of Five Leaves are very questionable, there's more to them than meets the eye and that's a theme in a majority of Ono's work. What we thought the characters were gets changed and so we're given a new perspective on the characters and it changes everything. She's great at slipping things right under you and subtly bring up into the story.
Another recommendation from Ono is Danza. It's a collection of sort stories about being a foreigner. The word foreigner takes many different meanings, from yourself, to your home, to the people around you and the culture your in. It's a quiet contemplative slice of life manga that I really enjoyed reading.
Before I go, I've recently fallen in love with Nakamura Asumiko artwork:
I just love her coloring and exaggerated character figures.