Born in Nagato province, he entered Nanzen-ji in Kyoto as an initiate or novice at the age of nine, and became a Buddhist priest at age 16, studying under the priest Keiho Genkin. While there he also studied Confucianism under Ishô Myôtei of Kennin-ji, and Keishô Zuidô of Tôfuku-ji, both of whom had studied in turn under Giyô Hôshû.
Keian joined a mission to Ming Dynasty China led by Ten'yo Seikei, which left Kyushu in 1468 and arrived in Ningbo a year later. Keian and the members of the mission received an audience with the Chenghua Emperor, after which Keian traveled to Suzhou and Hangzhou, and was able to study with a number of scholars of Neo-Confucianism. He spent six years in China, studying with these scholars and reading texts such as the Sishu jishi by Ni Shiyi from the Yuan Dynasty, and the Sishu xiangshuo by Cao Duan of the Ming.
He returned to Japan in 1473, and was forced by the chaos and violence of the Ônin War to move from place to place. After about five years of traveling around Iwami, Bungo, Chikugo, Suô, Nagato, and Higo provinces, he was invited to Satsuma by Shimazu Tadamasa in 1478. There, Genju first joined the Ryûun-ji temple. The following year, Tadamasa had a temple built for him, called Keiju-in or Tôin-ji, and he began teaching there. He was a strong advocate of Zhu Xi's interpretations, considering anything counter to Zhu Xi's theory to be "not academic." He is known to have lectured to Tadamasa himself not only on the teachings of Zhu Xi, but also of the Cheng brothers (Cheng Hao and Cheng Yi), who were significant influences for Zhu Xi, and on a text called Shujing jizhuan, by the Southern Song Dynasty scholar Cai Chen .
In 1481, he first circulated copies of Zhu Xi's Dàxué zhāngjù ("Passages from the Great Learning"), in a kakikudashi version, aiding readers incapable of reading classical Chinese directly in reading the text as Japanese. This edition, co-edited with Ijichi Shigesada, and known as the Ijichi-bon Daxue or the Bunmei-ban Daxue, was the first printing of Japanese commentaries on the teachings of Zhu Xi. Widely studied within the three provinces of the Shimazu domains, it was reprinted in 1492. Though none of the Bunmei originals survive today, one copy from the 1492 printing is extant in the Kaitokudô Bunko collection of the Osaka University Libraries.
Keian was invited in the late 1480s or early 1490s by Shimazu Tadakado (1439-1492) of Obi in Hyûga province to compose and otherwise handle documents related to Ming-Japan trade relations at Obi's Ankoku-ji temple and so Keian traveled between Obi and Kagoshima frequently for a time. He was offered prestigious positions at Kennin-ji and Nanzen-ji in Kyoto in 1498, but turned them both down.
In 1501, Keian wrote the Keian Ooshô kahô waten, conveying Japanese transliterations and reading methods for the Chinese classics, devised and taught by Giyô Hôshû of the Tôfuku-ji. This manuscript, and the techniques and approaches it contained, were passed down within a teacher-student lineage, from Keian Genju to Gessho Gentoku (1475-1541), to Ichiô Genshin (1507-1592), to Bunshi Genshô (1555-1620).
Keian also wrote a number of other texts, including Tôin gyoshô ("Fishing songs of Keian Genju", 3 vols.) and Tôin zatcho ("Various writings of Keian Genju", 1 vol.). He died in 1508, at a retreat called Tôki-an he established in Ijiki (today a neighborhood of Kagoshima City) in 1502. His grave can be found in Ijiki today.
- Gallery labels, Shôkoshûseikan, Kagoshima, Sept 2014.
- Takatsu Takashi, “Ming Jianyang Prints and the Spread of the Teachings of Zhu Xi to Japan and the Ryukyu Kingdom in the Seventeenth Century,” in Angela Schottenhammer (ed.), The East Asian Mediterranean: Maritime Crossroads of Culture, Harrassowitz Verlag, 2008. 255-257.
- Takatsu, 256.