Japan Railway, more commonly called JR, is a collective term for seven Japanese private railroad companies.
They are:
Here is some history of the Japan Railway, according to information provided by the Japan Railways Technical Research Institute ( http://www.rtri.or.jp/japanrail/JapanRail_E.html ):
October 14, 1872 - Opening ceremony at both Shimbashi (now Shiodome) and Yokohama(Now Sakuragicho)
October 1, 1907 - 17 private railways taken over by the government
December 20, 1914 - Opening of Tokyo Station
November 1, 1925 - Inauguration of the Yamanote Loop Line
December 30, 1927 - Inauguration of Tokyo subway between Asakusa and Ueno
June 1 1949 - Japanese National Railway organized
April 1, 1987 - Kokutetsu (Lit. Japanese National Railways; 国鉄 or 日本国有鉄道) was privatized and split into 11 companies.
See also: List of railway companies in Japan, Railroad, Private railroad, Shinkansen, Transportation in JapanHistory