Shanji
Shanji Trilogy, 1

Kati thought she was Tumatsin, but her real father was Moshuguang, a Searcher, one of those working to bring down the feudal empire on Shanji and establish a progressive society. Ruled by Mandughai, the emerald-eyed empress of a neighboring star, the Searchers are looking for the person who has inherited the power to be a super being. They believe Kati is that person, and with training from Mandughai, Kati's powers exceed her trainer's power. To bring unity to Shanji and to establish her rule, Kati finally realizes she must go to war with her beloved Mandughai.