We are presently in the early 18th century, during the Kyouhou period, when merchant society was thriving. Usugumo is a prominent courtesan with beautiful beauty and charm in Yoshiwara, Edo's red light district. She is, in reality, the daughter of a Christianized prostitute and Tokugawa Yoshimune (a genuine historical figure and the 8th Shogun of Japan), but the power struggle of the period prevents her from being with her father. When she meets the blond-haired burglar Kikunosuke, her fate is about to alter. Usugumo establishes the Kikugumi thieves group with Kikunosuke, a doctor named Aoto Touichirou who practices Western medicine, and her beloved cat, Kotetsu.