Aiun-ken Hugo Makibi Enomiya-Lassalle (1898-1990) was one of the most prominent teachers to embrace both Roman Catholic Christianity and Zen Buddhism. Enomiya-Lassalle was born in Germany and was ordained as a Jesuit priest. He travelled to Japan as a missionary in 1929, but became interested in that country's Buddhist practices. In 1940, he became the vicar of Hiroshima, and in 1945 he was critically wounded by the nuclear blast in that city. In 1956, Enomiya-Lassalle began studying Zen with Harada Daiun . In 1958, he published Zen: A Way to Enlightenmnet, but the Vatican ordered him not to continue publishing on the subject.

Following Harada's death in 1961, Enomiya-Lassalle became an apprentice of one of Harada's students, Yamada Koun . Yamada was enthusiastic about the possibilities of Zen as a Christian practice, believing that "Zen would become an important stream in the Catholic Church one day" [1]. With Enomiya-Lassalle's active assistance, he attracted a number of Catholic priests and nuns as students. In the late 1960s, Enomiya-Lasalle was certified as a teacher in Yamada's Sanbo Kyodan sect and given the title roshi, while professing his continued belief in Christianity. After 1968, Enomiya-Lassalle spent much of his time in Europe leading Zen retreats and encouraging zen practice among Christians.