I recommend reading Iwaoka Hisae's work - I think the only one published in English is Saturn Apartments, which is 7 volumes long. I'm a big fan of another of her series - Hoshigahara Aomanjuu no Mori - but I think that one might only be out in Swedish, not English. I also recommend Aki Irie's Ran to haiiro no sekai - which is planned to end with volume 7. Again, I don't know if it's released in English, but it's worth looking up for the artwork alone, which is gorgeous.
If we're talking graphic novels instead of manga, I recommend I Kill Giants. The artwork might put you off at first (it's kind of sketch-y), but it's a really, really good story.