"I am the king of Japan" and other nasty statements: Is there a reliable source on this?

I was reading Sensei's World article again — from Forbes — and researching about the following section:

Five years after gaining command of Soka Gakkai, he told a Japanese writer: "I am the king of Japan; I am its president; I am the master of its spiritual life; I am the supreme power who entirely directs its intellectual culture."

I really want this quote to be true, then we'll have an obvious piece of Ikeda's megalomania. But other links (this and this, for instance) only replicate the original, which have no source by itself. I can't use "a random Japanese writer" as source. Who's he? Where was it published? I truly don't think that those phrases came out of nowhere, but in order to have a trustworthy information based on evidence, I think it's important to refer where is that from. I'm giving a shot here before trying to contact Benjamin Fulford and David Whelan (Sensei's World authors) for further insight. Thanks!