Can you keep your Japan citizenship when you become a U.S. citizen?
Not allowed
No, in general
Japanese nationals who voluntarily acquire a foreign nationality, such as U.S. citizenship, automatically lose their Japanese nationality.
What the law says
- Japanese nationals who voluntarily acquire a foreign nationality automatically lose their Japanese nationality.
- Those who involuntarily hold a foreign nationality must choose between Japanese or foreign status before age 22, or within two years of obtaining the other nationality if acquired after age 20.
- Dual nationals who fail to make this choice can be required by the Minister of Justice to declare nationality within one month; further failure results in automatic loss of Japanese nationality.
- Foreign nationals naturalizing in Japan must renounce any previous nationalities.
“Japanese nationals who voluntarily acquire a foreign nationality automatically lose their Japanese nationality.”
What about the U.S. side?
The United States allows dual citizenship. At the oath ceremony you promise to renounce allegiance to other countries, but U.S. law does not make you formally give up your other passport. The question is only whether Japan lets you keep yours.
Source: Japanese nationality law (Wikipedia, summarized on 2026-11-11). Laws change — confirm with the Japan embassy or consulate before your oath ceremony. This is not legal advice.
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