Sonsei

Anime version The Son sister's aunt and Sonken's younger sister. While strict with her youngest niece, she is loyal to her Queen and niece, Sonsaku. However, it is later revealed that she strongly disagrees with the wars led by Sonsaku, which she believes will destroy Wu and the Son family. She and a group of nobles collaborated to have Sonsaku assassinated and take over the throne, but the plan fails thanks to a manipulating scheme by the Queen and her allies where she and the collaborators were arrested. (wikipedia.org)