Citizenship Through Parent (Jure Sanguinis)

You acquire Japanese citizenship by descent (jus sanguinis) automatically at birth if at least one parent is a Japanese national when you're born—or through a simple notification process if you were born out of wedlock to a Japanese father. The steps differ depending on where you were born and your family circumstances.

Children Born in Japan

Your child becomes a Japanese national automatically upon birth. You must register the birth within 14 days.

1. Gather your documents — Collect your child's birth certificate, proof of your Japanese nationality (Japanese passport or family register — koseki tohon), valid identification, and marriage certificate if applicable.

2. Visit your local municipal office — Go to the city/ward office (shiyakusho) in the jurisdiction where your child was born or where you're registered.

3. File the birth registration — Submit the birth registration form (shussei todoke). This simultaneously establishes your child's Japanese nationality and adds them to the family register.

4. Receive your child's family register entry — Once processed, your child appears on the family register and can obtain a Japanese passport.

Children Born Abroad to Japanese Parents

This is where timing becomes critical. You have exactly 3 months from birth to notify a Japanese embassy or consulate, or your child loses Japanese nationality retroactively. There are no extensions except in cases of force majeure (natural disaster, etc.).

Within 3 Months of Birth (Timely Notification)

1. Prepare your documents immediately — Gather your child's birth certificate, your proof of Japanese nationality (passport or family register), marriage certificate, and any other documents the embassy requests. All foreign documents must be apostilled (certified under the Hague Apostille Convention) and translated into Japanese.

2. Contact the nearest Japanese embassy or consulate — Find the Japanese diplomatic mission in the country where your child was born. Call or email to confirm their specific document requirements and appointment procedures.

3. File the birth notification and nationality retention — Submit the birth report (shussei todoke) along with the notification of intention to retain Japanese nationality (kokuseki ryoji todoke). This must be done within 3 months of birth. Some embassies allow mail submission; others require in-person appearance.

4. Await confirmation — Processing typically takes weeks to 1–3 months depending on the embassy's workload. The embassy will verify your documents and add your child to the family register in Japan.

5. Obtain your child's Japanese passport — Once the embassy confirms your child's nationality, you can apply for a Japanese passport at the same embassy.

Beyond 3 Months (Delayed Registration)

If you missed the 3-month deadline, your child has lost Japanese nationality retroactively. Recovery is possible but not guaranteed.

1. Prepare all documents — Gather the same documents as above, plus written explanation of why the deadline was missed.

2. Apply for citizenship acquisition — File an application for citizenship acquisition (kokuseki shutoku) with the Ministry of Justice through the local Legal Affairs Bureau (Houmu Kyoku) in Japan or through a Japanese embassy abroad.

3. Await Ministry review — The Ministry of Justice will review your application. Approval is not automatic and may be denied. Processing takes 1–3 months or longer depending on case complexity.

4. Receive decision — If approved, your child is added to the family register and can obtain a Japanese passport. If denied, you cannot reapply.

Children Born Out of Wedlock to a Japanese Father

Your child can acquire Japanese nationality through notification if your father legally acknowledged you (ninchi) before or at the time of your birth. You must file this notification before turning 18.

1. Ensure paternity acknowledgment is registered — Your Japanese father must have legally acknowledged you, and this acknowledgment must be registered in his family register (koseki tohon). If this hasn't happened, your father must complete it first.

2. Prepare your documents — Gather the acknowledgment form (available at the Japanese embassy), your birth certificate (apostilled and translated into Japanese), residence certificate (translated), proof that your father was a Japanese national at your birth, and your father's valid identification (passport).

3. Appear in person at the Legal Affairs Bureau or Japanese embassy — If you're 15 or older, you must appear yourself. If you're under 15, a legal representative (usually a parent) must appear on your behalf. Bring all original documents and translations.

4. File the notification — Submit the notification of acquisition of Japanese nationality. Once all requirements are verified, you acquire Japanese nationality immediately.

5. Obtain your family register entry and passport — The Legal Affairs Bureau or embassy will provide confirmation, and you can then apply for a Japanese passport.

Reacquisition of Lost Nationality

If you lost Japanese nationality because your parents failed to file the 3-month notification at birth, you can reacquire it—but only if you're under 18 and have an address in Japan.

1. Prepare your documents — Gather your birth certificate, proof that you lost Japanese nationality, and proof of your current address in Japan.

2. File the notification — Submit the notification of reacquisition at the local Legal Affairs Bureau in Japan or through a Japanese embassy abroad.

3. Acquire Japanese nationality — Upon approval, you become a Japanese national again and can obtain a family register entry and passport.

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Item	Cost
Government filing fee	Free
Document apostille (per document)	$5–$50 USD
Professional Japanese translation (per document)	$50–$200 USD
Postal/courier services	Variable
Travel to embassy or consulate	Variable

Total estimate: $0 in government fees; $100–$500+ USD in ancillary costs depending on the number of documents and translation needs.

Does not include: Costs for obtaining certified copies of foreign documents, expedited processing fees (if available), or legal consultation.

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Births registered in Japan within 14 days: Confirmation occurs within weeks. Your child is added to the family register immediately upon proper registration.

Births abroad — timely notification (within 3 months): Processing takes weeks to 1–3 months depending on the embassy's workload. Once the embassy accepts and verifies your documents, your child is added to the family register and can obtain a passport.

Births abroad — delayed registration (beyond 3 months): Ministry of Justice review takes 1–3 months or longer. Approval is not guaranteed.

Out-of-wedlock children — notification: Your child acquires Japanese nationality immediately upon notification, provided all requirements are met. The Legal Affairs Bureau or embassy will process the paperwork within weeks.

Reacquisition of lost nationality: Acquisition occurs immediately upon notification if you meet all requirements.

Factors affecting speed: Completeness of documentation, clarity of family relationships, embassy workload, and quality of translations. Missing or incomplete documents can delay processing significantly.