Keikoku

Profile

 * She tends to appear together with a foreigner who is bald and has a short moustache
 * She had a thin white butterfly bow on her hair.
 * She wears a partial Chinese Hanfu, along with a white transparent skirt which reveals her light pink panties.
 * Her name "Keikoku" means a woman destroying country with her beauty.
 * She mentions her other name is Yaobikuni.

Sengoku Rance
She doesn't appear in this route.
 * True History

She is one of the participants of the Emperor's Race which Kenshin is in.
 * Kenshin's Route

During the events of Isoroku's Route, she is one of the women who said that they had sex with Rance, and falsely states that her child with Steve is Rance's.
 * Isoroku's Route

She acts as Sounn's doctor and eventually mind controls him into opening the hellgates, effectively serving as the main antagonist of this route.
 * Ran's Route

Trivia
Real world reference: Yaobikuni / 八百比丘尼