Dual citizenship and multiple citizenship

Japan generally does not allow multiple nationality, except in limited cases where another citizenship is automatically acquired, eg at birth. Even then, such cases are intended to be temporary, with the individual ordinarily expected to choose one nationality by early adulthood.

Japanese citizens who acquire another nationality by choice will have their Japanese citizenship revoked under Japanese nationality law, and this revocation will be applicable from the date of voluntary acquisition of the non-Japanese citizenship.

In principle, naturalisation as Japanese requires individuals to renounce their non-Japanese citizenship(s). In practice, there are some cases of people with non-renounceable citizenships (eg Argentine) who are able to naturalise. There are also cases in which naturalisation as Japanese occurs before renuncication for foreign citizenship (eg US), allowing for temporary dual citizenship.

Despite this legal landscape which limits dual and multiple citizenship, approximately 1m Japanese citizens are dual or multiple citizens.

Legal framework

Under Article 11 of the Nationality Act, a Japanese citizen who acquires another nationality by their own choice forfeits their Japanese citizenship. This loss of Japanese citizenship even applies when parents (or others) make a choice for a Japanese child to gain another citizenship, as evidenced in these 2024 rulings and as explained in this Embassy of Japan in Los Angeles page.

Thus, dual or multiple Japanese citizenship (involving Japanese citizenship) is ordinarily limited to Japanese citizens who automatically acquired a non-Japanese citizenship, such as:

• a Japanese citizen born in the USA (automatically an American citizen via jus soli -- 'right of soil'),
• a Japanese citizen born in Japan to a British parent (who herself was born in the UK; the child would automatically be a British citizen by descent, via jus sanguinis - 'right of blood')
• a female Japanese citizen who married an Italian man prior to 1983 (automatically an Italian citizen via jus matrimonii - 'right of marriage')
• a Japanese citizen resident in a state which succeeds a previous state and automatically confers citizenship on residents (eg Mozambique, 1975)

As stated earlier, in such circumstances, dual or multiple nationality is only intended to be permitted until age 22 (or within 2 years of automatically acquiring a non-Japanese citizenship, if this happened after turning 20).

However, there is a twist. When such dual or multiple nationals reach the stipulated time for their choice of nationality (ordinarily age 22), they have an obligation to choose, and non-compliance can lead to revocation of Japanese citizenship in extreme circumstances. However, if someone chooses Japan, they then have a requirement to endeavour to renounce their non-Japanese citizenship(s), but there is no hard legal obligation beyond this, and no legal penalty for failure of those endeavours to result in renuncuation (indeed, some countries have no provisions for renunciation). Thus, dual nationals can, and do, live as dual nationals long beyond their stipulated choice of nationality date.

Travelling internationally as a dual or multiple citizen

Those holding Japanese nationality must enter and exit Japan as Japanese nationals.

The Immigration Control and Refugee Recognition Act states in Article 2.2:

the term "foreign national" means a person who does not have Japanese nationality (外国人:日本の国籍を有しない者をいう。)

There are separate sections of the Act regarding entry and exit procedures for Japanese citizens and foreign nationals, and because of the definition in Article 2.2, this means that Japanese citizens (including dual and multiple nationals) should enter and exit Japan as as Japanese citizens. It would not be appropriate for a dual or multiple citizen to enter as a foreign citizen, even from a visa exemption country such as the UK, as Japanese nationals cannot be granted a status of residence. The Act doesn't explicity state that a Japanese passport must be shown for Japanese entering Japan; the text refers to 'a valid passport', and 'passport' is defined in Article 2.5 as "a passport, a refugee travel document or any other certificate in lieu of the passport (including a travel certificate issued by a Japanese consular officer, etc.) issued by the Japanese Government, a foreign government recognized by the Japanese Government or any authorized international organization" (with a secondary note that equivalent documents may be acceptable). Some commentators therefore suggest it might be possible for a dual national to enter and exit using a non-Japanese passport (which would not be stamped by Immigration) together with proof of Japanese nationality (eg an expired Japanese passport); but due diligence would obviously be needed here, and it seems that even if this were possible in theory, in practice Japanese passports appear relatively easy to obtain by Japanese citizens and therefore workarounds like this seem unlikely to be applicable.

People with multiple non-Japanese citizenships

People who hold multiple non-Japanese citizenships will enter Japan using one of those citizenships. Should they become resident in Japan, their residency card will state one citizenship.