Japanese citizenship: naturalisation in Japan and the dual citizenship question

Japan is one of the countries that do not hand out their passport through an investor programme but through a statute in force since 1950: the Nationality Act, Kokusekihō in Japanese. It is short, clear and uncompromising on one point. Japan wants its citizens to hold just one nationality. That shapes every route to a Japanese passport, from naturalisation and marriage to the children of binational couples. Which countries make naturalisation through residence work well, and where it costs you something, is set out in the overview Naturalisation abroad. For Japan, it pays to read the statute closely.

How do you get Japanese citizenship?

Japanese law knows three routes: birth, notification and naturalisation. By birth you are Japanese if your father or mother is Japanese when you are born. A child born in Japan whose parents are both unknown or stateless also becomes Japanese. Beyond that, Japan has no birthright citizenship by place of birth: a child of German parents born in Tokyo does not become Japanese as a result.

Certain people acquire citizenship by notification to the Minister of Justice, for instance children under 18 whom a Japanese parent only acknowledged after birth. For everyone else there is naturalisation, Kika in Japanese. It is no formality but lies at the discretion of the Minister of Justice. The statute only lists the conditions without which he may not naturalise anyone. Meeting every condition still gives you no right to the passport.

For people with a special connection to Japan, the statute relaxes the conditions:

The article Citizenship by marriage compares the easier routes for spouses with other countries. For Japan this means: marriage shortens the wait considerably, but it does not free you from the condition that weighs heaviest for most Germans, the loss of your existing passport.

Naturalisation in Japan: the legal requirements

Article 5 of the Nationality Act sets six conditions. In its answers to frequently asked questions, the Ministry of Justice explains them as follows:

1. Residence: up to the application, you have lived in Japan continuously for at least five years, lawfully, with a valid status of residence.
2. Age and legal capacity: you are at least 18 and of full age under the law of your home country. Until 31 March 2022 the threshold was 20.
3. Upright conduct: the authorities look at criminal records, whether you pay your taxes and whether you have been a burden on others. The yardstick is the average citizen and general social standards.
4. Means of support: you can live in Japan without falling into hardship. The household is assessed as a whole: if you have no income of your own, the assets or skills of your spouse or other relatives you share a household with are enough.
5. No second nationality: you are stateless or lose your existing nationality when you are naturalised.
6. Loyalty to the constitution: you have never planned or advocated overthrowing the Japanese constitution or government by force, and you do not belong to any group that does.

What the Ministry of Justice also expects

Beyond the text of the statute, the ministry expects you to have settled into Japanese society. As examples it names Japanese good enough for everyday life, in conversation as well as in reading and writing, and, since 1 April 2026, generally a stay of ten years. So do not plan around the five years in the statute: they are the floor, not the norm.

The statute does not prescribe a language test at a fixed level. The ministry does, however, explicitly mention reading and writing, not just conversation. If you get by well in everyday life but can barely read kanji, that is where to start. How other countries handle language, tests and oaths of allegiance is covered in Language, tests and the oath.

Applying at the Legal Affairs Bureau

You do not apply at the immigration office but at the Legal Affairs Bureau for where you live, Hōmukyoku in Japanese. Some branch offices do not handle nationality matters. You must go in person and apply in writing; for children under 15, the parents or legal guardians act on their behalf.

Among the key documents, the Ministry of Justice lists:

• the application form with a photo,
• an overview of your relatives,
• a written statement of why you want to become Japanese,
• your CV, an overview of your means of support and, where relevant, of your business,
• your certificate of residence,
• proof of nationality, family relationships, tax payments and income.

As a rule, you prove your nationality and marital status with documents issued by your home country. If naturalisation is granted, Japan opens a family register of your own, the Koseki, and for that the bureau needs to know your family relationships precisely. The ministry explicitly advises talking to the Legal Affairs Bureau before you apply, because the documents differ by nationality, family and occupation.

The decision lies with the Minister of Justice. If he grants naturalisation, he publishes it in the Official Gazette, and from the day of that notice you are Japanese. The ministry does not name a fee or a fixed processing time; you clarify both with the Legal Affairs Bureau.

The Ministry of Justice publishes every year how many people take this route:

The figures show two things. Japan naturalises thousands of people every year, so the door is open. And the number of applications is rising faster than the number of naturalisations.

Dual citizenship in Japan and Germany: what applies?

Here two legal systems meet that run in opposite directions.

Germany has opened up. Under the Act to Modernise Nationality Law, section 25 of Germany's Nationality Act (Staatsangehörigkeitsgesetz, StAG) has been repealed since 27 June 2024. If you as a German acquire a foreign citizenship on application, you keep your German one, with no retention permit at all. The details are in dual citizenship for Germans.

Japan, by contrast, sticks to a single nationality. That shows in three places in the statute:

For you as a German, the first row means: Japan requires you to lose your previous nationality when you are naturalised. Because Germany no longer takes your passport away automatically, the way there is renunciation under section 26 StAG. Renunciation is only possible if you hold more than one nationality, it needs the approval of the nationality authority, and it only takes effect when the renunciation certificate is handed to you. What renunciation means for you and your family is explained in the article Giving up your citizenship.

Japanese law has one exception: if someone cannot lose their nationality at all, regardless of their own will, the Minister of Justice may still naturalise them where special circumstances exist, such as close family ties to Japanese nationals. For Germans it almost never applies, because German law expressly provides for renunciation.

The second row mainly concerns couples. A Japanese partner who is naturalised in Germany loses Japanese nationality, even though Germany would let them keep both. The same applies to any Japanese national who acquires a second passport of their own free will.

Children with one Japanese and one German parent

Dual Japanese and German citizenship most often arises at birth. A child with one Japanese and one German parent is both from birth. There are two deadlines you should know.

The first runs straight away: if the child is born outside Japan and also acquires another nationality at birth, the parents must declare within three months of the birth, at the Japanese embassy, a consulate or a municipal office in Japan, that they wish to retain Japanese nationality. This is done directly on the birth registration. Miss the deadline and the child loses Japanese nationality retroactively from birth. It can be recovered by notification to the Minister of Justice as long as the child is under 18 and lives in Japan.

The second deadline comes later: anyone who holds two nationalities before turning 18 must choose one by their 20th birthday. Anyone who only becomes a dual national at 18 or older has two years. If the child chooses Japanese nationality, it either gives up the other one or declares to the Japanese authorities that it chooses Japanese nationality and renounces the foreign one. Whether the foreign nationality actually lapses as a result is decided by the law of the other country; Japan then expects the person to make an effort to give it up. Anyone who does not choose at all may be asked in writing by the Minister of Justice to do so, and loses Japanese nationality if they do not choose within one month.

Can you buy Japanese citizenship?

No. Japan has no citizenship by investment programme, and there is no sum for which the statute grants the passport. The only shortcut past all the standard conditions is naturalisation for special services to Japan, and that needs the approval of the Diet. It is an honour granted case by case, not a route you can plan.

What capital gets you in Japan is a status of residence. The best known for entrepreneurs is called Business Manager, Keiei Kanri in Japanese. Since 16 October 2025, the Immigration Services Agency has required:

• capital of at least 30 million yen in your company; for sole proprietors, the amount you have invested in an office, one year of staff salaries and equipment,
• at least one permanent full-time employee who is Japanese or holds a settled status, for instance as a permanent resident or the spouse of a Japanese national,
• Japanese at B2 level for you or a full-time employee, shown for example by JLPT N2 or 400 points in the BJT test,
• a master's degree, doctorate or professional degree in a relevant field, or three years of experience in running or managing a business,
• a business plan reviewed by a professional such as a licensed tax accountant or certified public accountant.

An office in your own flat is generally no longer enough. And the status remains a temporary permission: it is granted for three months to five years, and at every renewal the authority checks taxes, social insurance and labour law. If you have spent a long time abroad without good reason, the renewal is at risk. How taxes, visas and daily life fit together in Japan is shown in Moving to Japan (in German), and the routes into the job market are covered in Working in Japan (in German).

Living in Japan without becoming Japanese

For most Germans in Japan, naturalisation is therefore not the first step but a decision at the end of a long road. Until then you live with a status of residence that has to be renewed. A visa is a permission. It can be refused, not renewed or revoked. Citizenship is a right, and that is exactly what you lack during those years.

This is where the idea comes in that the article CBI and naturalisation describes in detail: naturalisation is the free route to a passport, but it takes years and genuine residence. Citizenship by investment buys you the time. Japan has a particular twist here. Because Japan requires you to lose every other nationality on naturalisation, you would also have to give up a second passport from an investor programme when you are naturalised. For many people, a different combination is therefore stronger: live in Japan, keep the German passport and add a second passport as a safety net.

A second passport helps exactly where your status of residence leaves you exposed. If your German passport is lost, stolen or sits with an authority for weeks, you have a second travel document. And you have a second nationality for yourself and your children, whatever happens at the next renewal in Japan. These programmes are currently open and have a low entry point:

Sierra Leone accepts multiple citizenships without restriction, and Dominica requires no residence in the country either before or after naturalisation. All programmes, with family prices and processing fees, sit side by side in the comparison, and what an application costs in total is shown on the costs page.

Who the Japanese passport is still worth it for

For some people Japan is not a stop along the way but home. If you are married to a Japanese partner, are raising children in Japan and want to grow old there, naturalisation gives you real security: no more status of residence to renew, and the full right to live, work and vote in the country. For these people, swapping one passport for another can be the right decision.

Answer three questions honestly before you do:

1. Do you want to live in Japan for good? Japanese nationality replaces your German one; it does not add to it. Your right to live in Germany and the EU then depends on other rules.
2. Will you need another passport later? As a Japanese national you lose Japanese nationality as soon as you voluntarily acquire another. You can no longer add a second passport for emergencies after naturalisation.
3. What does it mean for your children? Children with one Japanese and one German parent are both from birth. They only have to choose by their 20th birthday. If your child is born outside Japan, those years with two passports depend on the three-month deadline after the birth.

If you can answer these questions clearly, Japan offers you a route you can plan. If you hesitate, you will often live more freely in Japan with your German passport and a second passport than with the Japanese one alone.

What taxes in Japan mean for you once you live there is set out in Taxes in Japan (in German). What a second passport means for tax if you are German is explained under Taxes and a second passport.

Frequently asked questions