Japanese Prefecture Codes: Complete List of All 47 Prefectures

import { subdivision } from '@koshmoney/countries';
 
subdivision.whereCode('JP-13');
// { code: 'JP-13', name: 'Tokyo', type: 'Prefecture', countryCode: 'JP' }
 
subdivision.whereCode('JP-27');
// { code: 'JP-27', name: 'Osaka', type: 'Prefecture', countryCode: 'JP' }

import { subdivision } from '@koshmoney/countries';
 
const allJP = subdivision.forCountry('JP');
// Returns array of 47 prefectures
 
// Build a dropdown
const options = allJP.map(s => ({
  label: s.name,
  value: s.code,
}));

import { subdivision } from '@koshmoney/countries';
 
subdivision.isValidCode('JP-13');    // true (Tokyo)
subdivision.isValidCode('JP-48');    // false (only 47 prefectures)
 
subdivision.isValidRegion('JP', '01');  // true (Hokkaido)
subdivision.isValidRegion('JP', '99');  // false

import '@koshmoney/countries/subdivision/JP';
import { whereCode, forCountry } from '@koshmoney/countries/subdivision';
 
const tokyo = whereCode('JP-13');
const allPrefectures = forCountry('JP');

import { postalCode } from '@koshmoney/countries';
 
postalCode.isValid('JP', '100-0001');  // true (Chiyoda, Tokyo)
postalCode.isValid('JP', '5300001');   // true (Osaka, no hyphen)
postalCode.isValid('JP', '12345');     // false (too few digits)

import { country } from '@koshmoney/countries';
import { currency } from '@koshmoney/countries/currency';
import { geography } from '@koshmoney/countries/geography';
 
country.whereAlpha2('JP');
// { name: 'Japan', alpha2: 'JP', alpha3: 'JPN', numeric: '392' }
 
currency.getCurrency('JP');
// { code: 'JPY', symbol: '\u00a5', name: 'Japanese Yen' }
 
geography.getContinent('JP');  // 'Asia'
geography.getRegion('JP');     // 'Eastern Asia'

import { subdivision } from '@koshmoney/countries';
 
const prefectures = subdivision.forCountry('JP');
// Already in numeric order (JP-01 through JP-47)
 
const dropdown = prefectures.map(p => ({
  label: p.name,
  value: p.code,
}));

const tokyoMetro = new Set(['JP-13', 'JP-11', 'JP-12', 'JP-14']);
const kansaiMetro = new Set(['JP-26', 'JP-27', 'JP-28']);
 
function getShippingZone(from: string, to: string): string {
  if (from === to) return 'same-prefecture';
  if (tokyoMetro.has(from) && tokyoMetro.has(to)) return 'metro';
  if (kansaiMetro.has(from) && kansaiMetro.has(to)) return 'metro';
  return 'standard';
}

function getRegion(prefectureCode: string): string {
  const num = parseInt(prefectureCode.split('-')[1], 10);
  if (num === 1) return 'hokkaido';
  if (num <= 7) return 'tohoku';
  if (num <= 14) return 'kanto';
  if (num <= 23) return 'chubu';
  if (num <= 30) return 'kansai';
  if (num <= 35) return 'chugoku';
  if (num <= 39) return 'shikoku';
  return 'kyushu-okinawa';
}