Freesia

Freesia is a twelve-volume manga series (adapted into a 2007 live-action movie) drawn by Jiro Matsumoto between 2003 and 2009. Set in an Alternate History Japan, rampant crime and dwindling resources due to a war with another nation led the government to passing the Vengeance Act to keep prisons from overfilling. As a consequence, instead of going to prison, victims of a crime can legally try to kill the perpetrator, or enlist the help of a proxy agency to have their enforcers do it for them. The target can also enlist the help of bodyguards to help defend themselves (in the event that the target can't find/afford any, the government provides bodyguards for him).

The story starts with the main character Hiroshi Kano applying for a job as an enforcer for one of the best proxy agencies. Kano has a special ability of being able to "disappear" by blending into his environment so well others literally can't notice him. He is also a very mentally unstable military veteran. Together with Wide-Eyed Idealist rookie Yamada and somewhat agressive mentor Mizoguchi, Kano begins his life as an enforcer...

Freesia follows the lives of our main cast, as well as the people that they interact with and how the Vengeance Act affects society as a whole. It's drawn with Matsumoto's distinctive dirty and sketchy art style. Like any Jiro Matsumoto manga, expect to see hallucinations, plot twists, and lots and lots of Mind Screw.

Tropes used in Freesia include:

The Alcoholic: Hisae (the female bodyguard protecting Terajima and Ide)
Dead All Along: Kano's girlfriend died somewhere in the middle of the story, and he never noticed it until authorities had to remove the decaying body.
Dirty Cop: Government-appointed bodyguards are very easy to bribe. Yamada doesn't like that at all.
Dissonant Serenity: Kano and Higuchi are always eeriely calm. Kano begins to show more emotion towards the end.
Doppleganger Spin: If somebody saw Kano when he activates his Invisibility, the person will still see an afterimage for a period of time, thinking that's the real Kano.
Forever War: Against and unnamed nation, from the everyday citizens' perspective. And they're losing. By the end of the story, the government surrenders and the Vengeance Act is abolished by the occupying force.
Grey and Gray Morality
Invisibility: Kano can blend into virtually any surrounding. How effective it is also depends on his mental state.
Knight in Sour Armor: Yamada, after a few missions on the field.
Lawful Stupid: Yamada is this in his presentation, Type 1,^[context?] although his character development sends him to Lawful Evil, in which the rest of the characters, especially Higuchi, also qualify.
Mind Screw: Matsumoto loves this trope, and his art style adds to the insanity. Have fun trying to pick apart what's real and what's not.
Only Sane Man: Yamada.
Sanity Slippage: Mizoguchi. Kano slides back and forth throughout the story.
Shaggy Dog Story: All the characters are, but Shibazaki up to eleven
Sliding Scale of Idealism Versus Cynicism: Pretty cynical, but doesn't go all the way.
Unreliable Narrator: We see events happening mainly through Kano's eyes, which makes us prone to his hallucinations.
Villain Episode: In Terajima's story arc, we get to see a proxy enforcement from the target's side.
Wide-Eyed Idealist: Yamada at the start of the story. Goes to Knight in Sour Armor territory in record time.