Do you speak Japanese? If not, how did you expect to have a meaningful interaction with Japanese people? The people you're talking about in rural America speak the same language as you.

I've gone many places in Japan and had meaningful interactions. There's definitely more of a divide between strangers and acquaintances than western countries, but I find rural Japan to be far more welcoming. I met a guy that's about 70 the other day while he was out working in his garden and we've chatted a few times over the past week because we're both out early in the morning. He gave me some eggplant and said he'd help me plant some strawberries if I want. We talked about his former job and we talked about our families. 

I get what you're talking about - Japan can definitely feel lonely. The big cities are probably quite bad in that regard. But it can be a warm and welcoming country as well.