There are good ways and bad ways to preserve a cultural identity.
Nationalism and Isolationism are bad ones.
True enough, but it’s not clear that’s what’s currently going on in Japan.
It may be that a certain amount of cultural protectionism (e.g. language, immigration numbers) is required in their situation; time will tell if they get the balance right.
In the first link I posted earlier (#3),
In recent years, the Abe administration has adopted major changes that will probably sustain the influx of immigrants. In 2017 Japan implemented fast-track permanent residency for skilled workers. In 2018 it passed a law that will greatly expand the number of blue-collar work visas, and — crucially — provide these workers with a path to permanent residency if they want it.
So Japan is beginning a major and unprecedented exercise, similar in some ways to the experiments embarked on by many European countries. Japan is still far from being a diverse country, but it’s no longer quite right to call it homogeneous. The next two or three decades will reveal whether the country’s culture and institutions will be able to learn from Europe’s experience and manage a smooth transition, or whether immigration will spark a nativist backlash that closes the country off once again.