Japan's 7-Digit Postal Code System

## The Japanese Format

Japan uses a 7-digit numeric postal code written as **〒123-4567**. The 〒 symbol (yuubin mark) is unique to Japan and is used on post offices, mailboxes, and postal materials.

The current 7-digit system was introduced on February 2, 1998, replacing the 3-digit and 5-digit systems that had been in use since 1968.

## Structure

| Digits | Meaning |
|--------|---------|
| 1st-3rd | Region and local delivery area |
| 4th-7th | Town, neighborhood, or building |

The first three digits identify one of Japan Post's delivery regions. The last four digits narrow the location to a specific town (chō) or even a large building.

## First-Digit Regions

| Digit | Region |
|-------|--------|
| 0 | Hokkaido |
| 1 | Northern Kanto (Saitama, parts of Tokyo) |
| 2 | Southern Kanto (Kanagawa, Chiba) |
| 3 | Northern Kanto (Gunma, Tochigi, Ibaraki) |
| 4 | Chubu (Shizuoka, Aichi) |
| 5 | Kansai (Osaka, Kyoto) |
| 6 | Kansai/Chugoku |
| 7 | Chugoku/Shikoku |
| 8 | Kyushu |
| 9 | Hokuriku/Tohoku |

## Precision and Address Integration

Japanese postal codes achieve high precision because they map directly to Japan's hierarchical address system: prefecture → city → ward → town → block → building number.

A single postal code often corresponds to a specific **chōme** (town section), meaning you can infer most of the address from just the postal code.

## Unique Characteristics

- **~120,000** active postal codes for 126 million people
- Large buildings (skyscrapers, government offices) may have their own postal code
- Japan Post provides a free lookup API and downloadable CSV
- Postal codes are written before the address (opposite to the US convention)