[xubzxnnm] Ninja

In the popular vein of "realistic with a touch of supernatural", create a show about a modern ninja, an unstoppable untraceable assassin for hire.

One of the conceits might be that the ninja's technique is never revealed; the targets just end up dead in random ways, and law enforcement, despite its best efforts, is unable to connect the deaths to the assassin.  Perhaps told from the ninja's point of view, or perhaps from society's view reacting to the existence of such an assassin.