I'm curious if anyone has read "A Buddhist Theory of Semiotics: signs, ontology, and salvation in Japanese esoteric Buddhism"? It describes itself as "a unique introduction to the important aspects of Shingon buddhism." The author is a professor of Shinto which is why I am curious about the book.
"Inscribed with the brush of Mt. Sumeru and the ink of the seas,
Heaven-and-earth itself is the sutra book.
All phenomena are encompassed in even a single point therein,
And the six sense objects are all included within its covers."
-Kukai, translated in Kukai on the Philosophy of Language by Takagi and Dreitlein