Kaoru Takamura's Lady Joker (volume 1) took me a while to finish, but it's not because it's not good, it's just very long and very detailed. It's definitely a psychological thriller in the sense that almost everything you read happens in people's heads, rather than any outright action. It's pretty scathing about capitalism, the Japanese corporate culture and the "keiretsu" system, with corporations in bed with organized crime.

But it ended on a cliffhanger, so even after 600 pages, I have no idea how it will end. Volume 2 will have all the answers i guess