Does Japan allow dual citizenship? The nationality law of Japan allows a single nationality in principle and does not allow dual citizenship. However, there are a large number of people with dual citizenship in Japan.
A person who has both Japanese and foreign nationality (dual nationality holder) must choose one of the two nationalities by a certain deadline (Article 14, Paragraph 1 of the Nationality Law).
A person who has both foreign and Japanese nationality must choose one of the two nationalities by the age of 20 if he/she is under 18 when he/she becomes a dual nationality holder, or within 2 years from the age of 18 or later (Article 14, paragraph 1 of the Nationality Law). If they do not choose, they may lose their Japanese nationality.
(The ages were lowered in April, 2022 because the legal age of adulthood was lowered from 20 to 18.)
Even if this deadline has been exceeded, the multiple nationality holder must choose one of the nationalities. Under the Nationality Law, the Minister of Justice may make a demand for the selection of Japanese nationality if the applicant does not select Japanese nationality within the time limit. In principle, the person who has been given such a notice will lose his/her Japanese nationality upon expiration of such period if he/she does not choose Japanese nationality within one month from the date of the notice.
According to the law, those who have dual nationality must choose one of the two nationalities, and if they do not choose, the government is supposed to advise them to choose a nationality.
However, in reality they have been no cases where the government contacted such people and ask them to choose a nationality.
Under the Nationality Law, if the selection of nationality is not made within the time limit, a notice of selection of nationality is given by the Minister of Justice, and if the selection of Japanese nationality is not made within one month from the time the notice is given, the applicant loses his/her Japanese nationality. However, in reality, there seem to be no cases where a notice is given, and the dual nationality is often left unchecked. Thus, even in Japan, where dual nationality is not permitted, there are likely to be many people with dual nationality.
Although the exact number is not known, it is estimated that there are between 400,000 and 500,000 people who have both Japanese and foreign citizenship.