Politicians in many countries adopt a nationalist approach towards present and projected population decline: they exaggerate how difficult it will be to cope with a decrease, and presume that the solution is to persuade young people to have more children. They don't recognize the future danger of a larger (or even unchanged) population, and disregard immigration as a way of reducing future decrease.

It is true that Japanese culture is very unfriendly to immigrants, but the state could do things to reduce that and help immigrants surmount the obstacle.