Kogetsu Zenzai

Kogetsu Zenzai (虎渓禅材, 1667–1751) was a Japanese Rinzai Zen master who played a central role in absorbing Ōbaku influences into the mainstream of the Japanese Rinzai tradition during the Edo period^[1]. Born in Miyazaki prefecture, he trained under Kengan Zen'etsu (1618–1696), whose own teachers had trained with the Chinese Ōbaku masters who came to Japan in the mid-seventeenth century. Kogetsu absorbed the more rigorous Chinese monastic style — including strict application of the Vinaya, Chinese-style chanting, and a demanding approach to koan practice — that the Ōbaku mission brought, and he propagated these elements throughout the Rinzai network from his base at Daiko-ji temple where he served as head monk^[1][2].

The so-called Kogetsu school of Rinzai became one of the principal vehicles through which Ōbaku reformist energy was transmitted into Japanese Rinzai practice. Hakuin Ekaku (1686–1768), who ultimately reformed and systematized all of Japanese Rinzai, regarded Kogetsu as a significant teacher despite disagreeing with him on the status of the great doubt and koan method; several of Hakuin's most important senior students had trained in Kogetsu's circle before coming to Hakuin. Among Kogetsu's dharma heirs, Gessen Zen'e transmitted the lineage to Gasan Jitō, one of Hakuin's foremost disciples, creating a genealogical linkage between the Kogetsu school and the lineage that now constitutes all surviving Japanese Rinzai^[2].