Kousonsan Hakukei

Anime version
A small feudal lord who wishes to protect her people from a recent rise of banditry. A noble person who loves her white horses.

In Shin Koihime Musō it is revealed that she is a childhood friend of Ryūbi Gentoku (the real one), and that she manage to gained possession of the latter's stolen sword before pawning it off to Enshō in exchange for food and support for her people much to her regret (she eventually recognized the sword's scabbard from their time as children). She accompany Ryūbi to try to get the sword back from Enshō but despite finding out Enshō no longer has the sword, Enshō decides to cancel Kōsonsan debt to her as compensation.

Visual novel version
A feudal lord who initially serves under the En faction before allying herself with the Shu faction. She has a greater role in Shin Koihime Musō.

(Source: Wikipedia)