He was born as the child of Toan IMAHORI, who practiced Confucianism and medicine, in Iba-go, Kanzaki District, Omi Province, (the present-day Higashiomi City, Shiga Prefecture) but he was mostly likely the illegitimate child of Motokatsu SONO of Gon Dainagon (provisional major counselor) and was later sent for adoption.
近江国神崎郡(滋賀県)伊庭郷（現滋賀県東近江市）の儒医今堀東安の子として生まれたとされるが、権大納言園基勝（そのもとかつ）の私生児でその後里子に出されたとの説が有力である。