# Find Japanese Postal Codes and Addresses

Japanese postal codes and town addresses can be difficult to match accurately. This skill guides local searches using Japan Post's official data without login credentials.

## Install

```bash
npx skillstore add tahodev/zipcode-lookup
```

## Metadata

- Status: approved
- Slug: tahodev-zipcode-lookup
- Skillstore revision: r1
- Version status: missing
- Tree hash: 855ef6c08952fc762df9582c99201e79c42ec54479a12e8dba7f0e71ce651e45
- Author: tahodev
- GitHub username: tahodev
- License: MIT
- Repository: https://github.com/tahodev/kurashi-skill/tree/09cb7f9eac85f0c85633cce08328a1a57854a94f/zipcode-lookup
- Ref: 7f17813fb6af1acc7d8fd3fb5f05480f5be52783
- Supported tools: Claude, Codex, Claude Code
- Audit status: complete
- Agent install advisory: allowed
- Manual install advisory: allowed
- Artifact signature: available
- Audit attestation: unavailable
- Human verification: not\_verified
- Risk factors: external\_commands, network, filesystem
- Quality score: 74
- Public page: https://skillstore.pages.dev/skills/tahodev-zipcode-lookup
- Manifest: https://skillstore.pages.dev/api/skills/tahodev-zipcode-lookup/manifest

## Capabilities

- Guide downloads of Japan Post's national UTF-8 postal dataset from its official download page.
- Search local CSV data by seven-digit postal code.
- Find postal codes through partial town-name searches.
- Interpret postal code, prefecture, municipality, and town columns.
- Return all matching rows when a postal code covers multiple towns.
- Explain download failures, user-assisted alternatives, and monthly refresh practices.

## Use Cases

- Check Postal Address Fields: Compare a customer's town and postal code against official postal data before updating an address record.
- Review Japanese Address Data: Find postal codes for town-name entries and identify ambiguous matches during data cleanup.
- Look Up a Town's Postal Code: Search a Japanese town name locally without creating an account or requesting an API key.

## Prompt Templates

### Look Up One Postal Code

```
Find the address for postal code 1000001 using Japan Post's UTF-8 dataset. Include all matches and the dataset month if known.
```

### Search by Town Name

```
Find postal codes for Marunouchi in Chiyoda City, Tokyo. Search the Japanese town name and include every matching town entry.
```

### Review Multiple Matches

```
Search the local dataset for postal code [seven-digit code]. Return every matching prefecture, municipality, and town, including any catch-all entry.
```

### Refresh and Verify Local Data

```
Refresh Japan Post's UTF-8 dataset in a dedicated directory and record its source and download date. Compare [town] matches with my existing dataset.
```

## Limitations

- Initial data acquisition requires network access or a user-supplied official archive.
- The author observed download failures from datacenter IP addresses; hosted agents may require a local-machine fallback.
- Postal address notation may differ from residential or registered addresses.
- Label printing, shipping, and Yubin ID conversion are outside this skill's scope.

## Best Practices

- Use the official UTF-8 dataset and extract archives into a dedicated directory after checking their contents.
- Record the dataset month when available and the download date; refresh approximately monthly.
- Return every matching row and distinguish postal notation from residential address notation.

## Anti Patterns

- Guessing postal codes or download URLs when official data is unavailable.
- Treating the first match as the only result for a shared postal code.
- Extracting an unchecked archive over unrelated workspace files.

## Security Audit

- Audited at: 2026-10-13T04:34:33.221\+00:00
- Summary: All 15 static findings are false positives involving Markdown formatting, legitimate downloads, fixed shell commands, and a documentation link. No evidence found of prompt injection, credential access, or data exfiltration. A separate low-severity concern is archive extraction that can overwrite local files without isolating the destination.

## Stats

- Views: 0
- Downloads: 0
- Favorites: 0
- Popularity score: 0