Yamada Koun Zenshin (山田 耕雲 Yamada Kōun, 1907—1989), or Koun Yamada, was the former leader of the Sanbo Kyodan lineage of Zen Buddhism, the Dharma heir of his teacher Yasutani Haku'un Ryoko. Yamada was appointed the leader of the Sanbo Kyodan in 1967, 1970 or 1973 and continued to differentiate the lineage from other Japanese Zen traditions by deemphasizing the separation between laypeople and the ordained—just as his teacher Yasutani had done. Yamada was also instrumental in bringing Christians to the practice of Zen that “by the end of Yamada’s teaching career approximately one quarter of the participants at his sesshins were Christians”.
