Set in an alternate history of Edo-period Japan, a mysterious disease known as the 'Redface Pox' has decimated the male population, leading to a society where women hold all positions of power, including the Shogun. The Ooku, the Shogun's inner chambers, becomes a harem of men serving the female ruler, serving as the epicenter of political intrigue, power struggles, and forbidden romances. The series follows the evolution of this matriarchal society across several generations, exploring the complex dynamics of the Shogunate as it navigates internal strife, external threats, and the burden of maintaining a legacy in a world fundamentally altered by the gender imbalance. It is a poignant examination of human ambition, sacrifice, and the search for identity within the rigid confines of the Ooku.