In the Tokugawa era, the dreaded redface pox is devastating the country's population of young men, and after a few generations, the gender ratio has fallen to roughly one male for every four females. Since sons rarely survive to adulthood, family trades are now passed from mother to daughter, and women hold even important governmental positions. In order to prevent the rest of the world from discovering this state of affairs, Japan institutes a strict isolationist policy, and female officials adopt masculine names so that even the official records don't reveal what's happening. Though the outside word is suffering from a shortage of marriageable men, the inner chambers of Edo castle are a lavish place, filled with hundreds of men who serve both as an emergency standing army, and also as the personal harem for the new shogun - a woman named Yoshimune who is determined to fix the rampant inequality and wastefulness of her country.