Otome Teikoku

Kanoko is the highly respected prefect of the dorm at a prestigious girls' boarding school. So much so that she is called the "Emperor" of the dorm. She and Tsumugihime, who is known for her beauty, play the role of an "ideal couple," but their true feelings are not so innocent. Because Tsumugihime has a secret that they doesn't know… (Source: Sukima, translated)