In the shadows of the Edo period, certain individuals are chosen from childhood and raised apart from the world — trained in isolation to become the shogun's secret agents. Ran Sagajo is one such person, a young woman whose entire life has been preparation for a mission she was born to fulfill. Accompanied by Sasuke, her loyal and inexplicably eloquent ninja squirrel companion, Ran sets out from their secluded village and heads for Edo to continue her training — and to begin the work she was always meant to do.