Historically: Second daughter of Sanjou Kinyori, Minister of the Left and second legal wife of Takeda Shingen, a woman of courtly blood who was mother of his original heir, Takeda Yoshinobu as well as two other sons and two daughters (the older of whom married Houjou Ujimasa). Her name is literally written as "person of Sanjou (Clan)".
She was described as a great beauty and fervent in her devotion to Buddhism. Since Shingen eventually named the grandson of a concubine heir to the clan, it is thought that Sanjou and Shingen did not get along.
In Mirage of Blaze: She and Kousaka Masanobu break the barrier over Takeda Shingen's tomb, the Maenduka, and attempt to resurrect Shingen by using Narita Yuzuru as a vessel for his spirit. She herself takes over the body of Takeda Yuiko but is exorcised by Takaya and Naoe with kouhou-choubuku.