Agent Douglas Walters

One of the few Agents willing to help Hito after the disappearance of Strykes, Walters was found dead in his Vegas apartment, nailed to the ceiling by a katana through the skull, and surrounded by the phrase "Stop asking questions" written in Japanese, and in his own blood.
The katana used to kill Walters is current in the possession of Agent Hito after it informed him that its erstwhile master wished to meet him on the "Highest span of the tallest bridge in London, from where his fall would be the farthest." The Agent appears to have accepted the challenge.