Phantom: Requiem for the Phantom

Phantom: Requiem for the Phantom is an anime series that aired in 2009, based on the video game Phantom of Inferno.

The story follows a Japanese national who tries to escape from an assassin syndicate called Inferno after personally witnessing an assassination while visiting the United States. Eventually getting captured and brainwashed by Inferno, the young man loses his memories and becomes the assassin code-named "Zwei".

Episode 1
Zwei takes off his gown while fighting Phantom.