I brought up the issue of diversity because as you confirmed, it seemed that Apple's company culture seemed to directly tie into why there was a such a "visual" diversity, and why it seemed fairly straight forward to apply there and get considered. It does seem that Apple culture has trumped Japanese business culture here. And that's no small feat.
I did my masters course work in government, with an emphasis on Japanese culture and politics, but with two other government comparisons: U.S. and Australian. Ironically, I visited Parliament in Canberra before I visited the U.S. Capitol, and I have still not visited the Kokkai. But my studies were only AFTER I had lived both in Japan and in Australia, versus every one else but my professor (whose wife is from Kyushu and whose children are dual nationals, and who taught constitutional law in Japan). It was also pretty much after that when I decided that Japan was my home, I belonged here, and I was committed to the cultural process of assimilation and the legal process of naturalisation. Otherwise, I might have gone back to Straya. Ironically, I believe Japan has given me more of a "fair go" than the U.S. ever did. But it could just have been my overtly socialist nature in the very libertarian American south.
I'm not a supporter of the jiminto (LDP), and I don't generally support Prime Minister Abe or his various supporting organisations. I'm more aligned with socialist or communist parties in Japan, but how I'll use my vote when I get it isn't something I know for sure. Abe, for his flaws, believes in civic nationalism. You are Japanese if the law says you are Japanese. Unfortunately, civic nationalism is still nationalism, and nationalism, as you point out, has serious issues, even if it is accepting of naturalised citizens.
I can't say I understand Japanese culture, but neither can most Japanese. I just live in it and generally accept it. It's funny to ask a friend to explain something and they can't. And I have found myself in the same position when friends or family from the States ask me to explain why I have developed a habit of this or that, and my sole response is, "Because Japan."