Akumetsu ~ Yoshiaki Tabata & Yûki Yogo
I just started reading this seinen... it's twisted so far, but awesome!
Nagasawa Shiina was just your average 3rd year high schooler when her parents' company went bankrupt. In order to pay the bills, her family sells her into prostitution. At her first job, a mysterious masked man crashes the party...and it's someone she knows...
Akumetsu is the story of Hazama Shou, who defends his own view of justice in a vigilante manner while wearing a mask and calling himself Akumetsu.
Edit: I'll try to revive this thread
This manga is quite a good one, basically a guy who seems to be somewhat omnipotent is disgusted by corrupt bureaucrats and business men and decides to use violence to change it, its pretty funny since the main character Akumatsu/Shou doesn't seem to take things seriously a lot of the time, especially when he's got someone tied up and is about to shoot their fingers off, or he has someone held hostage with a sword.
The violence isn't too bad considering it's a seinen although there is a lot of blood and random people do sometimes die.
Download chapters here or read online here
Some more pics and pages from the manga. (Maybe some spoilers)