Japan standard time

Japan Standard Time or JST (日本標準時 Nihon Hyōjunji or 中央標準時 Chūō Hyōjunji) is the standard timezone in Japan, and is 9 hours ahead of UTC, i.e. it is UTC+09:00. There is no daylight saving time, though its introduction has been debated several times. During World War II, it was often called Tokyo Standard Time.

Japan Standard Time is the same as Korean Standard Time, Indonesian Eastern Standard Time and Yakutsk Time.

Before the Meiji era (1868–1912), each local region had its own timezone in which noon was when the sun was exactly at its zenith. As modern transportation like trains was adopted, this practice became a source of confusion. For example, there is a difference of about 5 degrees longitude between Tokyo and Osaka and because of this, a train that departed from Tokyo would arrive at Osaka 20 minutes ahead of the time in Tokyo. In 1886, Ordinance 51 was issued in response to this problem, which stated:

Ordinance 51 (on the precise calculation of time using the Prime Meridian) - July 13, 1886

According to this, the standard time (標準時, Hyōjunji^?) was set 9 hours ahead of GMT (UTC had not been established yet). In the ordinance, the first clause mentions GMT, the second defines east longitude and west longitude and the third says the standard timezone would be in effect from 1888. Coincidentally, the city of Akashi in Hyōgo Prefecture is located exactly on 135 degrees east longitude and subsequently became known as Toki no machi (Town of Time).

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