Yamada Koun

The date is most likely 1973, however, as Charles S. Prebish writes in his book Luminous Passage: The Practice and Study of Buddhism in America,

It is likely the date is not 1967 or 1970 because Yamada would not need anyone's blessing to go to Hawaii were he already the head of the school, not to mention 1973 was the year of Haku'un Yasutani's death.

Yamada continued to study under Yasutani for seven years following this experience, and in 1961 he became the successor to Haku'un Yasutani—one year after completing some six hundred koans under him. There is some confusion over the date on which Yamada became the leader of the Sanbo Kyodan:

In 1953 Yamada invited Haku'un Yasutani to Kamakura and founded the Kamakura Haku-un-kai. Then, according to Stephen Batchelor,

Yamada Koun Zenshin (山田 耕雲, Yamada Kōun, 1907—1989), or Koun Yamada, was a Japanese Buddhist who was the 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”.

Yamada Koun was born Yamada Kiozo in Nihonmatsu in Fukushima prefecture of Japan in 1907. He attended school with Soen Nakagawa at Dai-Ichi High School located in Tokyo, Japan, and also went to university with him. In 1941 Yamada began working as a labor supervisor for the Manchurian Mining Company—a company known for poor working conditions and exploiting its slave labor forces composed of Chinese peasants, POWs and criminals. By 1945 he had become deputy director of the General Affairs Department for the company.