Ooku is the live action version of the manga of the same. The story sets in feudal Japan were men dwindled down in numbers due to an illness that only affects men and the shogun is a woman with a harem of men. It's basically the first part of the book and I hope there will be more. As I mentioned in my manga review, the movie also dabbled reverse harem element. The flick's a faithful interpretation of the story. If my memory serves me right there's just a couple of scenes that are not included in the manga. Maki Horikita is also part of the cast but just as a supporting character.