Japan: Cultural Homogeneity
Japan is a good example of a nation state. It's cultural homogeneity is overwhelming [jppeo].
The following is from the 1997 CIA World Factbook:
[http://www.odci.gov/cia/publications/factbook/index.html]
Ethnic groups: Japanese 99.4%, other 0.6% (mostly Korean)[jppeo]
Religions: observe both Shinto and Buddhist 84%, other 16% (including Christian 0.7%)
Languages: Japanese