In this alternate history of Edo-period Japan, an incurable disease has wiped out much of the nation's male population, leaving women to take up traditional men's roles, including that of shogun. As this series is structured, its first volume begins eighty years after the disease's initial outbreak, at which point the male population has declined by 75% and women have become firmly fixed in their new roles. The second and third volumes then return to the beginning of the outbreak, which finds the nation in a panic--desperate to maintain male rule, even to the point of delusion, if that is what is required.