Reduce the list, select first 2 letters of the city:
Listing cities (116 place(s)). Select the City to see the postcode(s):
Listing cities (116 place(s)). Select the City to see the postcode(s):
Position: Postcodes > Japan > Yamagataken > O.... >
Postcode finder: Japan, List of the cities starting with O. Japan Yamagataken Postcodes (Desktop version).