Mikage Kirio's ancestors were known as ninja in Japan before the Meiji Restoration forced them out of business. In modern times, the Kirio family operates the Shadow Village Company, providing specialized protection services to wealthy and important individuals. Mikage has been part of a team of bodyguards for the widowed Mr. James G. Rod since she was a child. Though frowned upon, she harbors strong feelings for her master, and in turn, she reminds Mr. Rod of the family that he once had. He proposes to adopt Mikage as his daughter, so that she can quit her dangerous profession and attend school like a normal girl.

However, the very next day after this offer was made, Mr. Rod falls victim to yet another assassination attempt. In the aftermath Mikage must decide if, and how, to fulfill her master's selfish last request.