What your readers are not getting:

This is not a problem for the planet, but it is a problem for the Japanese culture. Such readers probably don't care about that, but the Japanese people surely do.

Its really too bad that the Japanese culture is also quite closed to accepting new folks in as Japanese.

If there were a way to "Japanizing" immigrants in a way that felt satisfactory to the local population. This would become a non-problem. The country is wealthy and nice enough to drive huge levels of immigration.... and they could select for high productivity folks too.