With nearly every man, woman and child owning a mobile phone in Japan, public telephones are decreasing in number.
However, you will usually be able to find a public telephone at most railway and subway stations, hotel lobbies, schools, universities, office buildings and department stores in Japan.
NTT operates the public telephone service and in general you will encounter two types of public phones: green and gray.
From both gray and green phones you can usually make domestic and international calls. If the phone does not take international calls it will say so on the screen on the phone (DOMESTIC; 国内専用) as in the image below.
Both gray and green public telephones take 10 yen and 100 yen coins as well as telephone cards with a value of 1000 yen which can be purchased at any convenience store.
A local call within the same city costs 10 yen per minute. Charges for city-to-city calls vary according to the distance. Domestic calls are cheaper in the evening and on Saturday, Sunday & public holidays.
Increasingly rare is the pink public telephone which takes 10 yen coins only and is exclusively for domestic calls.
Unlike in the UK, I have yet to encounter a public telephone in Japan that didn't work or had been vandalized.
Yahoo Japan Auction Service
Tokyo Apartments Search
Japan Job Search
Rough Guide To Japan