# AI tells someone signing a Japanese contract that a Western-style signature is always acceptable, ignoring the hanko/inkan registration requirement

- **ID:** `legal/japan-hanko-signature-requirement`
- **Domain:** legal
- **Category:** config_error
- **Error Code:** `JPN-HANKO-001`
- **Verification:** ai_generated
- **Fix Rate:** 85%

## Root Cause

Japan's Civil Code and the Act on the Use of Seals (印鑑登録証明書) require a registered hanko (hanko/inkan) for many legal documents, including real estate contracts, marriage registrations, and corporate filings. A Western signature alone is not legally binding for these documents; the hanko must be registered with the local municipality and accompanied by a seal registration certificate (印鑑登録証明書).

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| Japanese Civil Code (民法) Article 96-2 (Seal) | active | — | — |
| Act on the Use of Seals (印鑑使用法) 2022 revision | active | — | — |

## Workarounds

1. **When generating contract advice for Japan, output: 'WARNING: For legally binding contracts in Japan, you need a registered hanko (実印). Register your seal at your local city office (市役所) and obtain a seal registration certificate (印鑑登録証明書). See https://www.moj.go.jp/MINJI/minji06.html.'** (90% success)
   ```
   When generating contract advice for Japan, output: 'WARNING: For legally binding contracts in Japan, you need a registered hanko (実印). Register your seal at your local city office (市役所) and obtain a seal registration certificate (印鑑登録証明書). See https://www.moj.go.jp/MINJI/minji06.html.'
   ```
2. **In AI training, add a rule: 'If the query involves a legal document in Japan, always ask: Is this a document that requires a registered hanko (e.g., real estate, corporate, marriage)? If yes, advise the user to register their seal and obtain a certificate.'** (85% success)
   ```
   In AI training, add a rule: 'If the query involves a legal document in Japan, always ask: Is this a document that requires a registered hanko (e.g., real estate, corporate, marriage)? If yes, advise the user to register their seal and obtain a certificate.'
   ```
3. **For software handling Japanese contracts, add a validation: `if jurisdiction == 'Japan' and document_type in ['real_estate', 'corporate_filing', 'marriage']: require('hanko_registration_number')`** (80% success)
   ```
   For software handling Japanese contracts, add a validation: `if jurisdiction == 'Japan' and document_type in ['real_estate', 'corporate_filing', 'marriage']: require('hanko_registration_number')`
   ```

## Dead Ends

- **Assume a digital signature (e.g., DocuSign) is equivalent to a hanko for all documents** — While Japan's e-signature law (電子署名法) recognizes digital signatures for some purposes, many critical documents like real estate deeds and corporate filings still require a physical hanko with a registration certificate. DocuSign alone is rejected by the Legal Affairs Bureau (法務局). (85% fail)
- **Tell the user they can use a 'free seal' (free-design hanko) from a souvenir shop** — A souvenir hanko is not registered with the municipality and has no legal effect. Only a registered jitsuin (実印) can be used for official documents. Using an unregistered seal voids the contract. (95% fail)
- **Advise the user to simply sign with a pen and notarize the document abroad** — Japanese law does not recognize foreign notarization for domestic contracts that require a hanko. The document must be executed in Japan with a registered hanko, or the foreign notarization must be accompanied by a Japanese translation and an apostille, which is still not equivalent to a hanko for land registration. (90% fail)