Just as we attempt to create who we individually are by various assumptions and appropriations, so too do nations presume an identity that is based upon a number of premises and importations. All of these resemble each other more than they differ, but some nations, and some people, require different models.
The processes of ethnogenesis -- the formation of ethnic groups -- in the Japanese archipelago have been distinguished by a degree of consensus that is unusual only in that it is so long-lived. The idea that culture and "ethnos" are closed, bounded units, that there is an essential Japanese psychic unity that permeates these various cultural building blocks -- these are perhaps anachronistic ideas, but they persist.
Their acceptance leads to a number of assumptions. Mark Hudson, author of this very interesting new anthropological study, suggests some of them. It is "accepted by many people in contemporary Japan that only ethnic Japanese can speak Japanese fluently; foreigners who become highly proficient in the language are usually seen as somehow threatening exceptions to the rule. . . . There is a similar widespread assumption that people who do not look Japanese cannot be Japanese citizens."