So far as can be discovered, before 1919 there were no Buddhist nuns in Taiwan. Now, however, Taiwan is famous for its nuns, who far outnumber monks. How did this come about? Between the two World Wars, several Japanese Buddhist sects proselytized in Taiwan. The Rinzai Zen was particularly active; they ordained some men but more women, and took some of those women to Japan for education. In particular, this was done by a monk called Gisei Tokai, who also established a (now defunct) Buddhist charity in Taiwan called Tzu Chi, like the current movement. Another link between this and today’s Tzu Chi is a nun called Xiu Dao, now in her nineties; in 1961-2 she was the companion of the young lady who was later to found Tzu Chi and become known as the Master Cheng Yen. Perhaps because of this influence from Japan, Tzu Chi has adopted some features of the Japanese religion Risshō Kōsei-Kai. This article sets these discoveries in a broader framework: the invention of “humanist” Buddhism by Tai Xu in the 1920s; the influence of Japanese Buddhism on him and of Japanese culture on Taiwan; and the role of the reformist Yin Shun.