Reduce the list, select first 2 letters of the city:
Listing cities (261 place(s)). Select the City to see the postcode(s):
Listing cities (261 place(s)). Select the City to see the postcode(s):
Position: Postcodes > Japan > Niigataken > O.... >
Postcode finder: Japan, List of the cities starting with O. Japan Niigataken Postcodes (Desktop version).