えと、日本人論と国体かな?
Seriously though, I think it is difficult to define, especially in English, what constitutes Japanese culture when the Japanese can't define these terms themselves in Japanese. The ones I posted above, "nihonjinron" and "kokutai," are very difficult to translate into English, and even when I try I still feel like I haven't done them justice because of all of the 論文 (papers, essays) that are constantly written in Japan about the issue. Add in English language scholars like Timothy Hoye, Edwin Reischauer, or Herbert Bix, and the issue becomes even more convoluted.
I can sit here and rattle off a list of
parts of Japanese culture, but will I really be defining what Japanese Culture
is inherently or fundamentally? And how do I deal with major changes under Meiji, or Taisho Democracy, or Imperial Japan during the first part of Showa, or Showa's promulgation of the 1946 constitution, or Post-War Japan under Showa, or changes under Heisei? And we'll have to seriously look at how Japanese culture is progressing and what it might look like under the reign of Crown Prince Naruhito...
The Japanese have always been able to adapt elements of non-Japanese culture and make it "和事" (Japanese Concept/Thing/Item). This was in large part why the Meiji Restoration was so successful and why Japan never fell to colonialism the way other Asian countries did. It was also the reason why Imperial Japan became colonial itself after being primarily isolationist under Meiji (Russo-Japanese war being a very notable exception), and why after surrendering, Hirohito was able to present pacifism and functioning democracy as "inherently Japanese" ideas, reaching all the way back into Japanese history to show the councils between the Emperor, the Shogun, the Daimyo, and the Samurai as the beginnings of representative government.
I can only answer in a conundrum wrapped in an enigma covered by a riddle: Japanese culture is, and has always been, exactly what the Japanese believe it to be.