Saiunkoku Monogatari

The story, which takes place in the fictional medieval empire of Saiunkoku, follows the adventures of Shuurei Kou, a descendant of a noble family that has fallen on hard times. Her father serves as librarian in the Imperial palace, a post which offers prestige and respect but little compensation. Shuurei teaches in the temple school and works odd jobs to make ends meet, but her dream is to pass the imperial examinations and take a post in government, a path forbidden to women. Shuurei's plans come to an abrupt halt when the Emperor's Grand Advisor makes a startling offer: join the imperial household for six months as the young Emperor's consort, and teach the Emperor to be a responsible ruler. If she succeeds, the financial reward will be great. The story details Shuurei's growing relationships with the Emperor and other members of the court, the intrigues that surround imperial politics, and Shuurei's commitment to better herself and her country.
(Source: Wikipedia)