Shuuyu Koukin

Anime Version
The kingdom of Wu's master strategist. She is a close confidant and lover to Queen Sonsaku who understands her Queen's ambition. She has sworn loyalty to her until their task is done.

Visual Novel Version
The strategist for the Go Faction. Her affection for Sonsaku goes so far that she is willing to sacrifice everything else for Sonsaku's dream. In the sequel Shin Koihime Musō, if Kazuto joins the Wu faction, Shūyu eventually dies in action at the end of the campaign after the Gi faction is defeated.

(Source: Wikipedia)