Citizenship Through Parent (Jure Sanguinis)

Automatic Acquisition at Birth

You acquire Japanese citizenship automatically if:

• At least one parent is a Japanese national at the time of your birth — This applies whether you are born in Japan or abroad. The parent may be your mother or father. You must have a legal parent-child relationship established at the time of birth.
• Your father was a Japanese national at the time of his death, even if he died before you were born — You can still acquire citizenship if your father held Japanese nationality when he died.
• You were born in Japan to stateless or unknown-status parents — This is a safeguard against statelessness and applies only when both parents are unknown or have no nationality.

Critical Requirement for Births Abroad: The Three-Month Notification Deadline

If you were born outside Japan to a Japanese parent, your parents must file a notification of intention to retain Japanese nationality with a Japanese embassy or consulate within three months of your birth. If they miss this deadline, you lose Japanese nationality retroactively to the time of birth. There are no extensions except in cases of force majeure (natural disaster, war, etc.). This is the single most important deadline in Japanese citizenship-by-descent law.

If the three-month deadline is missed, you can still apply for citizenship acquisition through the Ministry of Justice, but approval is not guaranteed.

Acquisition by Notification: Children Born Out of Wedlock to Japanese Fathers

You can acquire Japanese citizenship by notification if:

• Your Japanese father has legally acknowledged your paternity (ninchi) — This acknowledgment must be registered in your father's family register (koseki tohon).
• Your father was a Japanese national at the time of your birth.
• Your father is currently a Japanese national, or was a Japanese national at the time of his death.
• You are under 18 years of age at the time you file the notification — This age limit was reduced from 20 to 18 on April 1, 2022. Once you turn 18, you can no longer acquire citizenship through this pathway.
• You have never been a Japanese national.

Reacquisition of Lost Nationality

If you lost Japanese nationality because your parents failed to file the three-month notification after your birth abroad, you can reacquire it by notification if:

• You are under 18 years of age at the time of notification.
• You have an address in Japan at the time of notification.

Dual Nationality and Nationality Choice

Japan does not permit dual citizenship. If you acquire both Japanese and foreign nationality at birth and your parents file the three-month notification to retain Japanese nationality, you must choose one nationality by age 20 (if you became a dual national before age 18) or within two years of becoming a dual national (if you became one at age 18 or older). If you fail to choose, you may lose Japanese nationality automatically.

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