While the quote below is off the topic of Chigaku Tanaka and Japanese imperialism, I wanted to include it because it offers an interesting insight into the differences between Sōka Gakkai and Risshō Kōsei-kai on the topic of the supremacy of the Lotus Sutra.

A millennial vision of “world peace” is also central to the two lay Buddhist organizations, Sōka Gakkai and Risshō Kōsei-kai, the largest of Japan’s so-called New Religions and both based on the Lotus Sutra and the teachings of Nichiren. … Founded before the war, both achieved their greatest growth in the postwar decades. …

The two groups have different understandings of how the ideal society is to be achieved (Stone 1997). Sōka Gakkai maintains that only the spread of Nichiren’s teachings can bring about world peace; in the light of Nichiren’s Risshō ankoku ron, adherence to other, “false” religions is ultimately blamed for the tragedy of Japan’s defeat in World War Il. This conviction underlay the organization’s aggressive missionizing in the postwar years. Risshō Kōsei-kai, for its part, takes an ecumenical approach; the “Lotus Sutra” is understood as the fundamental truth—God, Allah, or the one vehicle—at the heart of all great religions. Its cofounder and longtime president, Niwano Nikkyō (1906-1999), was active in promoting worldwide interfaith cooperation for peace. Central to both organizations, however, is a progressive millennialism, pursued, not through the transformation of existing social structures (as advocated in Ishiwara’s postwar millennialism), nor through civil protest (as practiced by Nihonzan Myōhōji), but by personal religious cultivation and by working within the system for social improvement. Both groups hold that war and other social evils have their roots in the greed, anger, and delusion of individuals; therefore, it is individual efforts in self-cultivation and promoting harmony in everyday relations—rather than diplomatic or political efforts—that will fundamentally establish world peace. What is needed, in Sōka Gakkai parlance, is not social revolution but “human revolution,” the positive transformation of character said to come about through Buddhist practive.