Yoshimune Tokugawa, third daughter of Mmitsuada from the Kii branch of the Tokugawa family, ascended as shogun after Ietsugu's death. She inherited leadership amidst societal instability from the male-decimating redface pox plague. Her governance enacted rigorous austerity, dismissing many Ōoku courtiers and implementing economic reforms to increase treasury revenue. Adopting a pragmatic, inquisitive stance toward shogunate administration, Yoshimune questioned the tradition of women in authority being recorded under male names. She recognized this practice obscured demographic data and hindered governance. To probe the custom's origins, she consulted the Ōoku chronicles, the *Chronicle of the Dying Day*, guided by Head of Secretary Murase Masasuke. This investigation revealed Lady Kasuga's historical role in transforming the Ōoku into a male-dominated space to preserve the Tokugawa lineage after the original male shogun's death. Her leadership extended beyond administration. She actively pursued eradicating the redface pox, supporting research that identified bears as reservoirs of the disease. She also reorganized the expanded Ōoku, which housed approximately 800 men as symbols of shogunal prestige, targeting its extravagance and inefficiency to reflect her commitment to fiscal responsibility and social equity. Later, Yoshimune abdicated in favor of her eldest daughter, Ieshige. Despite this, she remained influential behind the scenes, as shogunate officials frequently sought her counsel over Ieshige's. Her personal life included relationships with multiple men, and she was known for spontaneous encounters, reflecting her straightforward demeanor. Her character arc reveals a ruler dedicated to transparency and pragmatism, driven to reconcile the matriarchal present with patriarchal vestiges in Tokugawa traditions. Reviewing the *Chronicle of the Dying Day* informed her policies and symbolized her effort to understand the societal shifts caused by the plague.