Sanbo Zen is a lay lineage of Zen practice which combines its Soto heritage with a program of Rinzai koan study.
It was created by two Soto masters, Daiun Harada and Haku’un Yasutani, who both felt that the actual experience of awakening had been lost from the institutional training found within the Soto establishment of their day, and turned to Rinzai koan training in order to reintroduce it.
Harada Roshi completed koan training under the Rinzai master Dokutan Roshi and received formal Dharma transmission from him, alongside the Dharma transmission he had already received with the Soto lineage, though he remained within the Soto school for the rest of his life.
In the mid 20th century his successor Yasutani Roshi left a prestigious position within the Soto school and set up a zendo in a small apartment in a Tokyo suburb, from which the Sanbo school grew.
In 1970, Yasutani Roshi resigned as the abbot of Sanbō Zen and was succeeded by Yamada Kō’un Roshi (1907-1989), who ten years earlier had been appointed one of Haku’un Roshi’s first Dharma successors. Following Kōun Roshi’s death in 1989,Kubota Ji’un Roshi (1932–) became the head of Sanbō Zen and served as abbot for 15 years, carrying on the school’s emphasis on the practice of zazen, koan study, and coming to realization.
The present abbot of Sanbō Zen is Yamada Ryō’un Roshi (1940–), who is the son of Kō’un Roshi and succeeded Kubota Roshi as abbot in 2004.