A few weeks ago a blogging confrère left a link to his site Becoming Legally Japanese.
I have had a look since and I recommend the site to you if you have an interest in citizenship law. The site is in English and has good information on how to become a Japanese citizen, and testimonials about why people have taken this step - the latter, of course, being the more interesting question. You can also read this Flophouse post by an American emigrant and long-term resident here in Japan who is also On the Path to Citizenship in Japan.
Citizenship in a democratic nation-state is an odd beast. It retains some characteristics of an older status - that of subject - in that it is a personal status between an individual and a state (or a monarch). But unlike subjecthood, it is (in theory) a status that a person chooses and can be renounced unilaterally. A citizen (in theory) does not need the permission of his state to sever ties with one country and attach himself to another.
The reality is more complex than that. Often, there are conditions to be satisfied before a person can change allegiance. Some sending states require that another citizenship be obtained prior to renouncing. This is meant to prevent people from becoming stateless persons; the ideal being that every individual must be attached to some state, somewhere in the world.
On the other side, the receiving country has more power. There is no absolute right to naturalized citizenship in any nation-state I know of. Governments and their citizenry can and do place conditions that must be met before they allow an individual to become a full citizen. In short, nation-states can be very selective about whom they accept for full membership. In those conditions we find a blueprint of sorts for what that nation-state thinks is the "ideal citizen" and what they believe their citizenship means.
One of the conditions of Japanese citizenship is that the new citizen renounce all other citizenships. The Land of the Rising Sun is well known for its rejection of dual or multiple citizenships. To be Japanese is to have allegiance to one state, Japan, and no other. Since the trend in citizenship law in the world is toward acceptance of multiple citizenship (even Germany has blinked), there is speculation that Japan, too, will change its ways.
Perhaps. And I say this because I am discovering that the current system is far more flexible than people think. There is the law and then there are the "facts on the ground." There are Japanese citizens in France who have become French citizens. The Japanese embassy in Paris is aware of this.
According to my source, they don't seek them out, but they will investigate if it comes to their attention - a Japanese citizen, for example, who has lived a very long time in France and cannot produce a French residency card when he visits the consulate for some reason or another. Since France and Japan do not exchange citizenship databases there is no easy way for the Japanese government to know that a Japanese national has become a citizen of the French Republic, or of any other country for that matter.
Where single citizenship can be enforced is when a person applies to become a naturalized Japanese citizen. The authorities can ask for documentation and proof of renunciation of all other citizenships, but even that isn't a sure thing. The Japanese authorities do make allowances for subjects of countries that do not allow for unilateral renunciation. Also, in some cases they have looked the other way unless the dual citizen is "outed" in some way so that it simply cannot be ignored.
So Japanese citizenship law is clear on the matter of dual citizenship, but the application of the principle is, well, a grey zone.
And that makes this post American had to forfeit naturalized citizenship due to hiding his lack of relinquishment up on Becoming Legally Japanese very interesting. Nation-states make citizens and they can unmake them, too. (For an excellent read about this I recommend Patrick Weil's outstanding The Sovereign Citizen: Denaturalization and the Origins of the American Republic.)
What is fascinating about denaturalization (taking away a person's citizenship) is that nothing shows more clearly the difference between birthright and naturalized citizens. In democratic nation-states it is generally very difficult to take away the citizenship of someone who was born with that citizenship. Usually it requires proof of some sort of extreme wrongdoing incompatible with citizenship and even then it's not a simple process. At least, not in our time.
Naturalized citizens, on the other hand, can be unmade more easily and the most common method is to prove that there was some sort of fraud involved. Even Hirsi Ali who was an elected member of the Dutch Parliament was not immune to charges that she obtained her Dutch citizenship fraudulently.
And that was the charge against this American emigrant to Japan who applied for Japanese citizenship, received it and then had it revoked. To make matters worse, the authorities did not reinstate his previous status, that of Permanent Resident; he was downgraded to Long-Term Resident. (See this site for a summary of the difference between the two.)
I will stop here and let you read the story for yourself. I would appreciate comments or corrections from those who know more than I do about Japanese citizenship law. It is an interesting case on so many levels, and I have the feeling that there is more to the story. In particular I was curious about his rationale for not taking the steps to relinquish his US citizenship. Note that both FATCA and the US Exit tax are mentioned in the article.