Tsuchimikado Bishu

Tsuchimikado Bishu (土御門美秋), born Urabe Bishu (卜部美秋), is a woman from Necessarius who was forced to change her family name to play the part of being a family member of Tsuchimikado Motoharu along with Ashiya Touzu.

She is the one who suggested that her fake son Motoharu adopt a girl to pose as his sister.

Etymology
Her name is part of the theme of the Tsuchimikado family being based on seasons. Part of her name can be translated as autumn (秋)

Background
After Tsuchimikado Motoharu was tasked with becoming a spy for Necessarius in Academy City and becoming an esper, Bishu was apparently tasked to play the role of one of his family members, not liking that she was forced to change her name. She suggested to Motoharu to adopt a sister from an orphanage outside the city to fool their intelligence department. Motoharu doubts it could work and that they would be outed in a matter of three days but Bishu states that three days is enough for the world to be changed.

Quotes

 * (To Motoharu, from NT 7) "If you are to fake your identity as a student, you must have all the relationships that come with it... In other words, a family."
 * (To Motoharu, ibid) "Three days is long enough for the entire world to change."