Kogetsu Zenzai
Kogetsu Zenzai was a Japanese Rinzai Zen monk who emulated Ōbaku-teachings into Japanese Rinzai Zen. His teacher Kengan Zen'etsu had trained under Chinese Ōbaku-monks, and Kogetsu Zenzai was one of the principal persons in assimilating their teachings. In contrast, Hakuin Ekaku opposed their influence, yet also stressed the need for rigorous practice. A number of influential students of Kogetsu Zenzai eventually also studied with Hakuin, creating the koan-system presently used within Japanese Rinzai-Zen.