Renjun (1464 - October 8, 1550) was a priest in the Muromachi period and the Sengoku period (period of warring states). He was the sixth son of the eighth Rennyo of Jodo Shinshu sect (the True Pure Land Sect of Buddhism) and Renyu, mother, and had the childhood name of Kotoku and the real personal name of Kanetaka.
At his older brother Jitsunyo's command, Renjun entered Kensho-ji Temple in Otsu Chikamatsu and established Gansho-ji Temple in Nagashima, Ise Province (Nagashima, Kuwana City, Mie Prefecture). Later he lived in Kensho-ji Temple (Yao City) and Koo-ji Temple in Kawachi Province. Renjun based in Kinai region unlike others of his brothers who had their footholds in Hokuriku region and he was a younger maternal half-brother of Jitsunyo, so Renjun naturally became Jitsunyo's adviser and accepted Ennyo, who had been intended to be Jitsunyo's successor, as a son-in-law married to his daughter. Although Ennyo died young, Renjun's daughter gave birth to a baby who later became Shonyo, the 10th chief priest of Hongan-ji Temple.
Renjun worked hard for the development of the religious community in Omi, Ise, and Kawachi Provinces, and when Jitsunyo died, Renjun was entrusted with the care of Shonyo, the grandson of both these brothers, and exerted leadership with his powerful voice within Hongan-ji Temple as the guardian of the future head of the sect in his childhood.
While his efforts in enhancing the religious community's leadership against Sengoku daimyo (Japanese territorial lord in the Sengoku period) in various places were appreciated, Renjun later turned tyrannical out of arrogance, falsely charging and excommunicating three times (in 1518, 1527 and 1532) Katada Honpuku-ji Temple (Otsu City), which was an influential temple within the religious community and had fields of propagation overlapping those of Kensho-ji Temple (originally only the head of the sect was allowed to pronounce excommunication, but Renjun took advantage of the vicarious execution of duties as the guardian of Shonyo and thus pronounced excommunication). Renjun's oppression incurred rebellions by his family and followers in the provinces, and this not only triggered an internal conflict called the Kyoroku-Tenbun War, but also led to the execution and banishment of his own brothers (Rennyo's children) and their families who confronted against Renjun in the internal conflict. In connection with this war, Renjun was also condemned for having left his grandson Shonyo behind when Yamashina Hongan-ji Temple was burned down by Harumoto HOSOKAWA and having then returned to Gansho-ji Temple where his son Jichie (also known as Jitsue) (Jodo Shinshu sect) was.
Despite that, Shonyo had complete trust in his grandfather Renjun who secured longevity until four years before Shonyo's death, so it is even said that Hongan-ji Temple was virtually controlled by Renjun while Shonyo was the head of the sect.