Has anyone taken a close look at the Library of Congress Japanese Censorship Collection and made use of it in their work? Some really fascinating digital materials there:
https://www.loc.gov/collections/japanese-censorship-collection/about-this-collection/
"The Japanese Censorship Collection contains 1,327 marked-up copies of censored monographs and galley proofs for approximately 1,100 titles, mostly from the 1920s and 1930s."