There are a few ways to gain a deeper access into a country, pretty simple stuff.
I know I brought this up before, but for you I would recommend becoming a guest speaker. I have done it in unmanned systems and it works great in terms of gaining access to locals and local flavor.
Take a look at the categories in this link:
Finding a keynote speaker for your conference or event
You are perfect for a few of them. There are hundreds of companies that match unique topics to speaking engagements all over the world.
Honestly the only other way to get where you want to be in Japan is to do what my son did: Language institute and stay with a local family for 6 weeks
