Definitely not Karai. She comes later.

From birth, Reiju was trained with the sole duty of eliminating the Storm Clan's enemies. But since childhood, her true loyalty has been to you, the illegitimate child of the clan leader.

Years later, after you staged a coup, failing to usurp leadership of the clan. You would have been killed, but Reiju saved you, running away to the badlands and is currently nurturing you back to health.