Here is the stat:

Nobel Laureates Population Laureates/Million

Japan: 25 150 M 0.16

Australia: 12 17 M 0.71
Austria: 21 8 M 2.62
Canada: 25 30 M 0.83
France: 68 60 M 1.12
Germany; 103 80 M 1.29
Israel: 12 8 M 1.50
Italy: 20 60 M 0.33
Russia: 27 150 M 0.18
Sweden: 31 10 M 3.10
Switzerland: 26 8 M 3.25
Netherlands: 20 17 M 1.18
UK: 163 80 M 2.03
USA: 361 300 M 1.20

So interms of both the total number and laureates per million, Japan is not impressive compared to other ‘old' players.

However, you may be correct that Japan's post-2000 laureates number is only second to USA. It is surely amazing.