Ōoku the hidden chambers begins during the reign of the shogun Yoshimune and follows a young man named Mizuno Yunoshin. Mizuno joins the Inner Chambers - a harem of men at the disposal of the shogun - after realizing that he will not be able to marry the woman he loves. However, anyone who enters the chambers can never leave and must live their life out as a member of the Inner Chambers. Within the first month Mizuno uncovers a shocking secret - the shogun is really a woman! The story then shifts to follow Yoshimune, the current shogun and her quest to learn the reason why female Shogun's must be presented as male to all but those within the Inner Chambers. She seeks out the oldest member of the Inner Chambers and from a chronicle that begins with the reign of Iemitsu, Yoshimune learns that the shogun was once a male and that in fact, the female line has been kept only because of the red face pox. This deadly disease affected boys and young men and almost always resulted in death. Unable to stop its spread, the male population of Japan dwindled away eventually killing the shogun as well. Japan converted to a matriarchal society, where men became precious treasures to be protected and where they could sell themselves as prostitutes to women willing to pay the high price to have a child. Reversing the roles between men and women affected every level of society, including the shogunate where Tokugawa Iemitsu became the first female shogun.
