Rensei (1455 - September 17, 1521) was a priest of Jodo Shinshu (the True Pure Land Sect of Buddhism) who lived from the mid Muromachi period to the Sengoku Period (Period of Warring States). He was the fourth son of Rennyo, who was the eighth chief priest of Hongan-ji Temple. His real name was Kaneyasu (康兼), and his childhood name was Kogyoku (光玉).
He was entrusted to Nanzen-ji Temple at a young age. It is said that he was later sent to Yoshizaki Gobo, which was the destination of Rennyo who fled from persecution by Enryaku-ji Temple and decided to propagate in Echizen Province, as a hostage (attestant) of followers in Echizen who were preparing for Rennyo's settlement. Later, in 1476, when Rennyo conflicted with Masachika TOGASHI, who held the position of Kaga no Shugo, he contacted his oldest brother Junnyo to extricate their father. After staying in Yoshizaki for a while, he joined his second older brother Renjo who had fled to Ecchu Province. It is said that he practically lead the ikko ikki (an uprising of Ikko sect followers) in Ecchu in 1481, in place of his sickly older brother. Later, he moved to Yamada in Kaga Province (present-day Kaga City, Ishikawa Prefecture) and built Kokyo-ji Temple. After Hongan-ji Temple took control of Kaga in 1488, Kokyo-ji Temple of Rensei, along with Matsuoka-ji Temple of Renko, who was his older brother, and Honsen-ji Temple of Rengo, who was his younger brother and the successor of his older brother Renjo, came to be called 'Three Temples of Kaga' or 'Three Mountains of Kaga', and became the deputy governing institutions of Hongan-ji Temple in Kaga. However, because Rensei was linked to Ecchu monto (followers of Ecchu Province), the province was practically governed by the 'Goryozan' system by the two temples other than Kokyo-ji Temple, and Rensei assumed the position of an assistant. However, after Rennyo, who was his father, died, it is said that Jitsunyo, who was Rennyo's successor and Rensei's paternal half-brother, and Rensei didn't get along with each other and Rensei collaborated with Renjun, who was his younger brother, to transfer the head temple to Kaga.
But Kensei, who was his successor, son, and a renowned great scholar of the sect along with Rengo, was persecuted by Renjun's Hossu (the head of a Buddhist sect) empowerment policy and excommunicated. Although he restored his position later by the will of Renjun, he was confined due to an internal strife 17 years later, and led a turbulent life, until he died in 1570 at the age of 72.