Masaharu Anesaki’s book, “Nichiren, The Buddhist Prophet” was originally published in 1916 but is now in the public domain. It is available on the web without charge in a number of electronic formats.
Masaharu Anesaki, M.A., Litt.D., was a professor of the Science of Religion at the Imperial University of Tokyo and a professor of Japanese Literature and Life at Harvard University. The 1916 edition was published by Harvard University Press.