Sonken Chuubou

Anime version
Princess of Wu, second sister of the Son Family, and Shōren's older sister. Unlike her older sister, she is less ruthless, uneasy about herself, and more kind-hearted. She worries about how her sister's wars are affecting everyone which, unknown to her, her sister is doing is for their sake. Her sister has chosen her to be her successor; she knows that she will be a better ruler who will heal the wounds the nation has suffered from the wars.

Visual novel version
She is the leader of the Wu faction. She is insecure about being a ruler and questions herself often. She also possesses poor fighting skills; failing to land even a single hit on Kan'u before being defeated. After her defeat, she begins to develop feelings for Kazuto as he accepted her as a woman rather than a king.

In the remake Shin Koihime Musō, her older sister Sonsaku takes her place as the leader of the Wu faction. Her hair has also been greatly lengthened. However if Kazuto joins the Wu faction, Sonsaku is eventually killed in action early in the campaign, and Sonken takes over with a heavy heart, cutting her hair upon doing so.

(Source: Wikipedia)