Japan's Perspective on Dual Citizenship
Note that if your country allows dual citizenship, then even if you must "choose" in Japan, your country may allow you to retain that citizenship. The United States is one example of this. But I have heard from a US Embassy staffer personally, that as long as you don't become a government employee, you can still get away with dual US/Japan citizenship if you are born with it.
The following information sheet is published by the Japanese Ministry of Justice.
CHOOSING NATIONALITY
Persons holding both foreign citizenship and Japanese citizenship (dual nationals) must, before reaching age 22 (or, if having acquired dual nationality after age 20, within two years of acquisition) choose a single nationality.
If you do not choose a nationality, you may lose your Japanese nationality. Because of this, it is important to consider this issue carefully.
For additional details, please consult the nearest city, ward or town office, the Legal Affairs Office (Homukyoku) or Japanese Embassy or Consulate abroad.
WHO MUST CHOOSE A NATIONALITY
According to Japanese law, for dual nationals there is a specific period of time within which one must choose one's nationality. As regards the acquisition of dual nationality, there are the following five examples:
A child born to a Japanese citizen father or mother and a mother or father from a country that allows transmission of citizenship by a parent of either gender (for example, France).
A child born to a Japanese citizen mother and a father from a country whose laws provide for transmission of citizenship only through the father (for example, Korea).
A child born to a Japanese citizen mother or father, or two Japanese citizen parents, in a country whose laws provide for acquisition of citizenship by birth in that country (for example, the United States).
A child of a Japanese citizen who is legitimated by a foreign father's declaration of paternity (for example, Canada), by a foreign parent through adoption (for example, Switzerland), or through marriage to a foreigner (for example, Switzerland).
People who have acquired Japanese nationality through naturalization, or by filing a declaration of acquisition of Japanese nationality, but who did not forfeit their former foreign nationality, must also choose which nationality they wish to hold.
HOW TO CHOOSE YOUR NATIONALITY
For Japanese citizens holding a foreign nationality, below are listed the methods for declaring a single nationality. When the time comes to choose one nationality, think carefully and then make your decision known by one of the following methods.
ABANDONING YOUR FOREIGN NATIONALITY
Based on the applicable foreign law, submit to the nearest city, ward or town office, or to a Japanese Embassy or Consulate abroad, the form Gaikoku Kokuseki Soositu Todoke, showing your abandonment of your foreign nationality. For specifics on the procedures for renouncing a foreign nationality, please consult directly with the foreign government or its representatives.
SWEARING TO JAPANESE NATIONALITY
At the nearest city, ward or town office, or at a Japanese Embassy or Consulate abroad, you must state your decision to choose Japanese nationality and abandon your foreign nationality on a special form called the Kokuseki Sentaku Todoke.
ABANDONING JAPANESE NATIONALITY
At the Legal Affairs Bureau (Homukyoku) office with jurisdiction over your area, or at the District Legal Affairs Office (Chiho Homukyoku) with jurisdiction over your area or at a Japanese Embassy or Consulate abroad, submit your Family Registry (Kosekitohon), proof of address, proof of foreign citizenship, and a completed notification of abandonment of Japanese citizenship (Kokuseki Ridatsu Todoke).
DECLARING YOUR FOREIGN NATIONALITY
According to the laws of the specific foreign country, declare your citizenship and then present proof of your status as a national to the nearest city, ward or town office, or to a Japanese Embassy or Consulate abroad. You must then complete a notification of loss of nationality (Kokuseki Soositu Todoke).
THE PERIOD WITHIN WHICH YOU MUST CHOOSE YOUR NATIONALITY
As regards the period within which you must choose a nationality, the following time periods apply:
For Japanese citizens who became dual nationals before January 1, 1985 (i.e., before the change in Nationality Law was enacted):
If you were less than 20 years old on January 1, 1985, choose by your 22nd birthday;
If you were 20 years old or older on January 1, 1985, choose by December 31, 1986;
If you did not choose your nationality within these periods, it is assumed that you chose Japanese nationality.
For Japanese citizens who became dual nationals on or after January 1, 1985 (i.e., after the change in Nationality Law was enacted):
If you became a dual national before age 20, choose by your 22nd birthday;
If you became a dual national at age 20 or later, choose within two years of acquiring your foreign nationality .
If you do not choose a nationality within the time period specified above, the Minister of Justice (Homudaijin) will request you to make a final decision. This process may result in the loss of Japanese nationality.
