Kakujin (1021 - 1081) was a priest of the Enryaku-ji Temple who lived in the middle of the Heian period. His father was FUJIWARA no Tadatsune, Sama no kami (Captain of Samaryo, Left Division of Bureau of Horses), (a son of FUJIWARA no Michiyori, Gon Dainagon (a provisional chief councilor of state)).
He served his apprenticeship under Meikai, the 32nd Tendai-zasu (head priest of the Tendai Sect). At the time of the construction of the Hossho-ji Temple which was begun in 1075, he was put in charge of its doshi (officiating monk), and at the time of rakkei kuyo (a memorial service to celebrate the construction of a temple) in 1077 he was assigned to the gon no betto (a provisional superior of a temple). In the same year, he assumed the position of the 35th Tendai-zasu. He had served in Gonsojo (the lowest grade that can be held by one who has reached the highest rank in the hierarchy of Buddhist priests) and the zasu of the Hojo-ji Temple, and called himself as Kongoju-in Temple's zasu.
He was relied on heavily by the Emperor Gosanjo and the next Emperor Shirakawa, and was consulted about various matters in both religious and civil areas. In addition, he taught Chujin, the Otani-zasu, as his disciple.