I am afraid you are picking out things you want to see in comparing the US and Japan. You can’t find two more different countries and two different schools of thought on conservatism.
Over the last 30 odd years, Japan has made several small efforts to open up to foreigners more and in most cases, regretted it. For example, after admitting people from certain Middle Eastern countries on extended visas, they were flooded with visa overstayers (many who turned to petty crime). These attempts are not widely known as Japan almost always acts bilaterally. They’ve always been open to visas for which there is an underserved labor market.
But you are right that Japan is in a deep hole in regards to its economic and social fragility. They are not doing well. They got where they are through their own unique choices. But their unique choices are significantly different from ours.