Operating as a thief in early 18th century Edo during the Kyouhou era, Bentenkozou Kikunosuke is distinguished by his blond hair and chivalrous practice of stealing from the wealthy to aid the impoverished. His path crosses with Usugumo, a high-ranking courtesan of Yoshiwara's Miura-ya, and Aoto Touichirou, a practitioner of Western medicine. Together, they form the thief group Kikugumi.

Kikunosuke's versatility shines through his adept use of disguise, including posing as a Kyoto Shimabara courtesan. This skill proves vital for the Kikugumi, allowing them to navigate Edo's complex social terrain and evade pursuers. He becomes essential in protecting Usugumo, whose secret heritage as the daughter of Shogun Tokugawa Yoshimune and a Christian courtesan marks her for assassination by political enemies and the predatory heir of the Kaga clan.

His actions with the Kikugumi draw them into conflict with a mysterious faction wielding advanced weaponry like electrically powered gadgets and mechanized dolls. Kikunosuke stands as a key figure defending Usugumo, collaborating closely with Aoto to counter threats against her life and secure her future amidst the intense political intrigue surrounding her existence.