Not sure how interesting this is, but since the article mentions Scandinavia and "homogeneous society", that's not really true either. Unlike Japan, Sweden keeps track, not of "race" but country of origin for migrants or children of migrants.

For Sweden, 36.5% of men aged 15-44 are either foreign born, or has at least one parent foreign born. This data is from the Statistics Sweden (SCB) for 2019.

In this cohort, 62.5% are from, or have a parent from, Africa/Asia (Middle East), 9.3% from Western Europe/USA, 3.5% from the other Nordic countries, an 24.7% are from "Other" countries.

I'm not sure about the data for the other Scandinavian countries.