Yuizen (1253-March 23, 1317) was a priest of the Jodo Shinshu (the True Pure Land Sect of Buddhism) in the late Kamakura period. His father was Zennen ONOMIYA and his mother was a daughter of Shinran, Kakushinni. His given name was Hiromasa. He was called Dainagon (chief councilor of state) Ajari (a master in Esoteric Buddhism; a high priest). He was the kaisan (a founder of a temple as the first chief priest) of Saiko-in Temple (Jokyo-ji Temple as it is known today) in Sekishuku, Shimofusa Province.
He was first adopted by Shosho (minor captain) Suketoki and then by Dainagon Masatada. While he began his studies learning about Esoteric Buddhism, he also pursued the way of Shugendo (Japanese mountain asceticism-shamanism incorporating Shinto and Buddhist concepts). After that, Yuizen received outside help from Yuien (Yuien of Kawada) and converted to Jodo Shinshu. As requested by his elder brother Kakue, Yuizen lived in Otani, Kyoto. When the Senju Nenbutsu (the Single-Minded Recitation of the Nenbutsu) was threatened to be prohibited in the Kanto region in 1303, Yuizen went down to Kanto to protect it. He then had a dispute with Kakunyo, Kakue's child, about the succession of the Otani-byodo Mausoleum and capitulated, returning to Kamakura in Sagami Province with the head of the founder's statue.