As same as in other countries, the number of public telephones in Japan has decreased rapidly in 21th century, especially when people start using mobile phones.
Before the introduction and widespread of mobile phones, many Japanese used everyday when they were on the way home. They called their wifes, families or boyfriends/girlfriends from terminal stations, telling that expected time of arrival. There were even people waiting the vacant public phones even if there are 10 public phones at the stations.
The peak was in 1984, when the number of the public phones was 934903, but the number reduced even before the introduction of mobile phones, in 1990 was 832735, which means 100000 phones were removed in 6 years. Till 1995, there were more than 800000 phones in Japan but reduce to half in 2005. There were only 171179 phones in 2015.
Public phones are located each 500 meters in urban area and 1 km in rural areas but this system is not working in some places, especially in Oita prefecture which seems than 87.1% of the area does not have any public telephones. On the other hand, there are still public telephones on selected trains, especially Shinkansen and limited express. The first public telephone on train appeared in 1957.
NTT, Nippon Telegram and Telephone which operated these public telephones kept secret about the locations of these public telephones due to preventing thefts and the misuse, but finally revailed the locations of the public phones to the public in June 2012.
Public telephones accept telephone card and coins but only 10 and 100 yen coins. Purchasing the telephone card is getting difficult since the reduction of the public telephones.