This is totally anecdotal but a friend of mine grew up in Japan and from her experience, young people were much more racist than the geezers lol.

But yeah surprisingly most japanese want more immigration. But of course its not out of any affinity for multiculturalism, they just see the writing on the wall in regards to their demographic decline and want more working age people.

The “West” will have similar numbers in 10 years, the “Middle East” and “South Asia” in 20, and “Sub-Saharan Africa” in 30

Your population WILL decline and since this a worldwide phenomenon you can’t use infinite immigration to stave it off (as if it’s necessarily a bad thing) - you can actually but then countries which provide immigrants face the twofold pressure of high emigration and low natural growth and have steep declines particularly in working-age adults (already the case in Eastern Europe)