Shogun's Harem: The Mansion of Evil Spirits.

In the era of the ninth shogun, Ieshige, the Ooku of Edo Castle was a world of only women, with Tokiwa at the head and numbering up to a thousand. The town girl Otoshi catches the eye of Oitsu-no-kata and is brought into the Ooku. Oitsu receives the favor of Ieshige and is blessed with an heir, but Oko-no-kata resents Oitsu to the point of wanting to curse her to death. At that time, rumors of an evil spirit in the unopened room spread throughout the Ooku.