Side Note : If I were only talking about Japanese Documentaries instead of Documentaries about Japan...

According to From Grierson to the Docu-soap: Breaking the Boundaries, a collection of essays from a similarly titled conference ont he documentary held in 1999, there's an essay on the imapct of Paul Rotha, a contemporary of Greirson, a highly influential documentarian, on the Japanese fiml analyst scene post WWII. Again we see the bounce of western philosophic/theory thought within the Japanese context, especially considering the hot era of post WWII when the Americans were running the Occupation.