Supported document type
Detect tampered and deepfake My Number Card (Japan)
The My Number Card, マイナンバーカード, is Japan's free IC identity card, issued through municipalities, and it carries the holder's name, address, birth date, sex, and photo. Its twelve-digit My Number ends in a check digit and sits on a specific face of the card, so fabricated numbers and rearranged layouts leave checkable traces, while era-style dates add a second consistency test.
API slug: japan_my_number_card
Last updated:
What a genuine My Number Card contains
The My Number has twelve digits: eleven base digits and a final check digit computed from them. The card prints name, address, date of birth, sex, photo, and an expiry date, and the number itself appears on the back rather than the front. The IC chip and its PIN are not visible, so analysis works from the printed face and the number.
Dates are often printed in the Japanese era format, currently Reiwa, so the Gregorian year must be derived and compared rather than read directly. Address changes can be added later, newer layouts differ from the 2016-era design, and the card is not the same document as a residence card for foreign residents. Validity runs ten years from issue for adults and five for minors, which anchors the date checks.
How My Number Card forgeries are made
My Number check digit
The twelfth digit is calculated from the first eleven with a mod 11 weighting, so a number that fails the calculation was typed in rather than issued.
Era-year conversion
Era-style years must convert to the printed Gregorian date. A Reiwa year that does not agree with the date beside it is a contradiction a forger can easily introduce.
Expiry term logic
Adult cards run ten years from issue and minors' cards five. An expiry that does not fit the issue date and the holder's age breaks the issuing rule.
Face and layout placement
The My Number is printed on the back of the card. A number appearing on the front, or a layout mixing the older and newer designs, signals assembly rather than issue.
Photo and text patching
Substituted portraits and edited name or address lines leave cut-line edges, resolution steps, and font passes that localise the edited region.
What TamperCheck checks on a My Number Card
TamperCheck runs 200+ forensic checks across three layers and returns a risk score from 0 to 100 with plain-English findings tied to specific regions of the document. These three carry the most weight on this document class.
Portrait substitution and face-swap analysis
The document is isolated from whatever it was photographed on, then the portrait region is assessed against the card surface around it. A pasted or generated face rarely matches the substrate it was placed onto.
Date and validity consistency
Issue, expiry, and period dates are checked against one another and against the file's own creation metadata, which catches backdating and validity extension.
Reference and document number checks
Document, account, and reference numbers are checked for issuer format conformance and against every other place the same value appears on the page.
And many more checks
The three above are the layers that carry the most weight on a My Number Card. Every upload runs the full suite of 200+ checks regardless of document class, spanning file structure and metadata, pixel-level forensics, font and text rendering, optical and print characteristics, provenance signals, AI-generation signatures, and many more checks.
Who verifies a My Number Card, and why
Japanese banks, telcos, and eKYC providers. In each case the document is being used to unlock money, access, or a legal status, which is exactly what makes it worth forging.
How to verify a My Number Card in 4 steps
Photograph every face
Capture the front and the back flat at full resolution, so the My Number, era dates, and expiry survive close analysis.
Validate the My Number
Apply the mod 11 check-digit computation to the first eleven digits and compare with the twelfth.
Convert and compare dates
Convert era years to Gregorian, then test the birth date, issue date, and expiry against the ten-year and five-year terms.
Run a forensic check on the file
The check digit carries the structural story, and the print carries the edit history. TamperCheck runs 200+ forensic checks including check-digit validation, era-date conversion, and patch detection, returning a risk score from 0 to 100 with findings tied to specific regions of the image.
Frequently asked questions
How is the My Number check digit calculated?
The first eleven digits are weighted and summed, the sum is taken mod 11, and the check digit is eleven minus the remainder, or zero when the remainder is zero or one. A number that fails this was typed rather than issued.
Why does a Japanese card show a year like Reiwa 5?
Japanese documents commonly print era years, and Reiwa began on 1 May 2019. A year is not wrong if the era year converts to the printed Gregorian date, so the useful test is conversion, not appearance.
How long is a My Number Card valid?
An adult card runs ten years from issue and a card for someone under eighteen runs five, with a separate electronic certificate valid five years. The adult age threshold was lowered from twenty to eighteen on 1 April 2022.
How does TamperCheck verify a My Number Card?
TamperCheck validates the check digit, converts era dates and tests them against the issue and expiry terms, confirms the number sits on the expected face, and inspects the portrait region for patching. Uploads run through a single REST endpoint, are processed ephemerally and not stored, and findings tie to specific regions.
TamperCheck analyses my number card (japan) uploads with a hybrid forensic and AI pipeline tuned for this document class. Upload endpoints accept PDF and common image formats; class is inferred automatically. See the API documentation for authentication, async jobs, and webhooks.