He was born as the second son of Kimihiro YAMAMOTO of the Yamamoto family (the descendants of Saionji family), a branch family of the Abe clan, and became a priest and took the tonsure at Daigomuryoju-in Temple, to name his Kaimyo (a posthumous Buddhist name) 猶海.
阿野家の分家である山本家の山本公弘の二男（西園寺家末流）として生まれ、醍醐無量寿院において出家得度し、戒名を猶海とした。