Tokugawa Iemitsu, born Chie, was the illegitimate daughter of the third Tokugawa shogun. After her father succumbed to the redface pox—a plague devastating Japan's men—her grandmother, Lady Kasuga, the shogun's former wet nurse, forced her to impersonate him. This deception required her to live publicly as a man while confined within Edo Castle's Ōoku, a traditionally female space transformed into a male harem in this matriarchal society. Her childhood held deep trauma, including witnessing Lady Kasuga order her mother's execution to remove rivals. Manipulated and isolated, she endured treatment as a reproductive vessel, called "nothing but a walking womb" to bear a male heir. Bitterness, distrust, and emotional instability defined her early years, worsened by forced political rituals and encounters with male concubines. Arikoto Madenokoji's arrival, a Buddhist monk conscripted into the Ōoku, sparked transformation. Initially hostile, she slowly forged a profound emotional and intellectual bond with him. Arikoto saw her humanity and political capacity, affirming her identity beyond reproduction. This connection nurtured her into a shrewd, decisive leader. She displayed sharp political skill by revealing her true gender and the original Iemitsu's death to Japan's feudal lords. She leveraged their own struggles with male heirs to win acceptance of her rule, setting a precedent for female shoguns and female-led inheritance across the domains. Despite her union with Arikoto, they remained childless due to his sterility. Pressured to secure succession, she conceived three daughters with other concubines, including Gyokuei. Her physical and emotional strength faded, leading to her death at age twenty-seven. On her deathbed, she appointed Arikoto as Senior Chamberlain to guide her eldest daughter and successor, Ietsuna, ensuring his role in upholding the new social order. Her legacy endured within the "Chronicle of the Dying Day," a secret record commissioned by Lady Kasuga documenting the female shogunate's origins and the redface pox's societal upheaval. Discovered later by the reformist shogun Yoshimune, the chronicle revealed Iemitsu's foundational impact on Tokugawa governance and gender roles. Her reign initiated lasting traditions: female shoguns and officials using male names in official documents and the Ōoku's institutionalization as a male consort system. These practices persisted until the Meiji Restoration erased her history.