Yakushin (827 - April 8, 906) was a Shingon sect priest in the former Heian period. His secular surname was Ki clan. He was Gyokyo's real brother. He was born in Bizen Province. He was also called Enjoji Sojo and Hongaku Daishi. He was the founder of Hirosawa school of Shingon sect.
He first studied Hosokyo-sect under Myosen, studied the doctrine of the esoteric Buddhism under Shuei, and received kanjo (a ceremony to be the successor) from Gennin. He was designated as Gon-Risshi (generally in Shingon sect, fifteenth-ranking Buddhist priest, literally, "supernumerary master of discipline") in 888, and then promoted to Sojo (high-ranking Buddhist priest). During that time, he also worked as To-ji Choja Homu (Director of Temple Affairs and the chief abbot of To-ji Temple), Todai-ji Betto and Kengyo (temple or shrine administrator) of Iwashimizu Hachiman-gu Shrine. In 899, when the Retired Emperor Uda became a priest, he worked as Uda's mentor for his receiving the religious precept and later gave Uda kanjo as well. Yakushin also made FUJIWARA no Yoshiko, Naishi no tsukasa (female palace attendant) a Buddhist, her Higashiyama mountain villa was donated as a temple and he named it the Enjo-ji Temple. After that, his school came to be called Hirosawa school.