Background
He became adopted heir of his grandfather Saneyori, the head of Ononomiya family (小野宮家), and he inherited vast estate and documents of Ononomiya family.
藤原 実資後小野宮
He became adopted heir of his grandfather Saneyori, the head of Ononomiya family (小野宮家), and he inherited vast estate and documents of Ononomiya family.
He became udaijin (Minister of the Right) in 1021, and lived to be ninety. Sanesuke had a thorough knowledge of customs and rites, so he was called Kenjin Ufu (賢人右府) (wise Udaijin). He wrote the diary Shōyūki (小右記) for fifty years.
Sanesuke is mentioned in the Diary of Murasaki Shikibu, author of Genji Monogatari.
In it, she praises him for being out of the ordinary, and describes in detail a number of occasions of his superstitious behavior. Neither of these two marriages produced a child.
Later in life, he fathered two children by maids. Ryōen (良円) - priest
Chifuru (千古) (daughter) - married to Fujiwara no Kaneyori (son of Fujiwara no Yorimune)
Two adopted children are the sons of Fujiwara no Kanehira.
Kanehira was Sanesuke"s elder brother.
(adopted son) Sukehira (資平) (986–1068) - heir of Ononomiya family
(adopted son) Sukeyori (資頼).