The things about this concubine, including her existence, is not clear at all, but it is highly possible that she is a daughter of the Ujiie clan or a powerful local lord of West Mino associated with the Ujiie clan because of the following data: Nobutaka was placed with Yukihiro UJIIE, the second son of Naomoto UJIIE of the Three of West Mino; when Naoshige UJIIE, the first son of Naomoto, supported Nobutaka (信孝) at the battle of Nobutaka ODA (織田信孝) versus Hideyoshi, Nobutaka (信高) was also placed in confinement at home in Utsunomiya with Yukihiro (being placed in confinement at home can be interpreted as having been implicated as a relative).
この側室については存在を含め一切不明であるが、後に信高が西美濃三人衆の氏家直元の次子である氏家行広に預けられていること、直元長男の氏家直重が織田信孝と秀吉の戦いに際して信孝についた折、行広と共に信高も宇都宮で蟄居していることから、氏家氏か氏家氏ゆかりの西美濃の有力国人の娘である可能性が高い（蟄居するということは、縁者として連座したと解釈できる）。