Oooku

In an alternative timeline of feudal Japan, a strange disease that only affects men has caused a massive reduction of male population, thus women have to pick up men's jobs, changing the social structure. Now, after 80 years of the initial outbreak and current man:woman ratio of 1:4, Japan has become completely matriarchal, with women holding important political positions and men being their consort. Only the most powerful woman -- head of Tokugawa shogunate -- can keep a harem of handsome yet unproductive men, known as "Ooku."
Recipient of special prize at The Japanese Association of Feminist Science Fiction and Fantasy's fifth annual Sense of Gender awards (2005), Excellence Award for manga at Japan Media Arts Festival (2006), Grand Prize in Osamu Tezuka Cultural Prize (2009), Tiptree Award (2010)
Nominated for the first annual Manga Taish? (2008).
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From the creator of smart, sensual and wry stories like Antique Bakery and Flower of Life, comes a historical manga set in the era of samurai with a twist: What if most of the men were wiped out by a plague, and what if the shogun was a woman? The result is Ooku: The Inner Chambers, a historical fantasy series about a once-male dominated society turned inside-out, and a female Tokugawa-era shogun who keeps a harem of handsome male consorts for her pleasure.