To what extent is Theravāda followed in Japan? Extract from Ven. Nyanatiloka's Bio says


  In 1920, after being denied re-entry into British ruled Sri Lanka, Nyanatiloka taught at Japanese universities for five years, including at Taisho University where he was assisted by the legendary eccentric Ekai Kawaguchi, and at Komazawa University where he taught with President Yamagami Sōgen (山上曹源), who had also studied Pali in Sri Lanka. He also met with Japanese Theravada monks. He lived through the 1923 Great Kantō earthquake, which destroyed Tokyo, but was surprised to see universities reopen just two months later.


To what extent is Theravāda followed in Japan? To what extent is it taught or studied there? Has Japan produced any Theravada Scholars or Meditation Masters? Which books have they written?
In Japan in 2003 the number of Buddhist temples were


30,000 Pure Land 
21,000 Zen 
15,000 Shingom 
14,000 Nichiren 
5,000 Tendai


The source for this is Introducing Buddhism by Peter Harvey (pp 409 2nd Edition)

There is a Japanese Theravada Association which claims thousands of members and the Dhammakaya movement has six centres in Japan. However this appears to be a more recent phenomena and the above figures appear to indicate that it is a small movement in the context of Buddhism as a whole in Japan.