if 'we' is employed people, with an historic family link to the country ...i agree. For Japan or anywhere else.

If fertility statistics are propped up by the long-term unemployed ? not so much. And if all the old nation fails to reproduce while any newcomers are the only ones reproducing.....the Japanese would not embrace that willingly. Clearly it would be taking on the characteristics more of a colonization than demographic continuity.

Already seen in some populations of American-indians......effectively removed from the archive of history. First they stopped having babies, then Europeans moved in and did.

Lessons for the UK ?
Maybe young Nigel & Sharon need to get off the pill and bear the consequences ? broke ? so what, the Blitz generation had it harder than you.