The objective of this paper is to illustrate elite women’s political contributions and agency through a case study of Taira Shigeko/Kenshunmon’in. She was the “primary” wife of monarch Go-shirakawa, the mother of monarch Takakura, and a sister-in-law of Taira Kiyomori. Since the Heike regime brought “warriors” to the center of the court for the first time, its military aspect has been emphasized. By examining the sociopolitical structures of the insei period, however, it is apparent that violence alone would have never been enough to both establish and maintain the regime: both civil authority and military power were required. Through a biography of Shigeko, I explore how elite women in this period wielded power through civil authority and conclude that Shigeko was the co-founder of the regime that became a bridge to Japan’s first shogunate. Moreover, by positioning the Heike regime as the Go-shirakawa-Heike medieval ie, I demonstrate the shift of women’s expected role from that of “mother” to “wife.” As co-manager of the ie, medieval women held authority, and with their initiatives and agency, they could also wield tremendous power in the ie.