Phantom of Inferno

Phantom of Inferno visual novel game created by Nitroplus, directed and written by Gen Urobuchi, distributed in North America by Hirameki International (a subsidiary of the Japanese visual novel publisher Hirameki).

The game spawned the following media
 * A 2-volume light novel series written by Gen Urobuchi and illustrated by Konchiki. It was published and serialized by Kadokawa Sneaker Bunko from June 1 to December 1, 2002.
 * A 3-episode OVA directed by and created by studios Earth Create and KSS which were released from February 27 to November 26, 2004
 * A 3-volume seinen manga series by Masaki Hiragi and serialized in Media Factory's Monthly Comic Alive magazine from May 23, 2009 – March 23, 2010.
 * A 26-episode anime TV series adaptation created by Studio Bee Train and licensed by Funimation. It aired in Japan from April 2 to September 24, 2009.

Plot
Mafia is rife in America where assassinations are a regular occurrence on the streets. Inferno, a mysterious company, is behind most of these dealings through the use of their near-invincible human weapon, "Phantom."

One day, a Japanese tourist accidentally witnesses Phantom’s latest murder. Desperate to escape, the tourist hides in a secluded building. However, Phantom, revealed to be a young woman named Ein, and the leader of Inferno ‘Scythe Master’ captures the tourist and brainwashes him.

Given the name ’Zwei’, this once peaceful tourist is now a puppet of Inferno with no memories. Drawn into a world of lies, deceit, and violence, Zwei must fight to survive, hopefully to one day regain his memories and escape from this world where he is constantly on the brink of death.

Other Wikis

 * Phantom of Inferno Wiki (wiki about the game the anime is based)