"Yamanaka Sadao ni Sasageru Manga Eiga 'Nezumikozō Jirokichi'" is an anime series that adapts the classic Japanese manga and film centered around the legendary figure Jirokichi, a Robin Hood-like character from the Edo period. The narrative revolves around Jirokichi, a skilled thief known as the "Rat Boy," who steals from corrupt officials and wealthy merchants to aid the poor and oppressed. His exploits are set against the backdrop of a rigid feudal society, where the divide between the ruling class and the common people is stark.

The story begins with Jirokichi operating in the shadows, using his cunning and agility to outwit authorities and redistribute wealth to those in need. His actions earn him both admiration from the downtrodden and the ire of the shogunate, which dispatches skilled samurai and detectives to capture him. Throughout the series, Jirokichi faces numerous challenges, including betrayal, narrow escapes, and moral dilemmas, as he navigates the complexities of his dual identity as both a criminal and a folk hero.

Key characters include Jirokichi himself, whose charisma and resourcefulness drive the narrative; Oshizu, a loyal ally who aids him in his missions; and Inspector Zenigata, a determined lawman tasked with bringing Jirokichi to justice. The interplay between these characters adds depth to the story, highlighting themes of justice, loyalty, and the struggle against systemic oppression. The series blends action, drama, and historical elements, offering a compelling portrayal of a figure who defies authority to fight for the marginalized.