Citizen, like its Japanese bretheren Seiko, launches limited edition watches to commemorate special dates - like this full-serviced 1972 Citizen Ref. 4-673760-K mechanical watch issued to celebrate the 100th anniversary of the Japanese Government Railway (JGR, later known as the Japanese National Railway), which comes with its original commemorative Citizen D51 medallion, Citizen price tag, original Citizen leather strap, and inner & outer Citizen boxes.
 
The Class D51 (D51形) steam engine locomotive was built by the JGR (founded in 1872, hence the 100th anniversary nature of this watch), the Japanese National Railway (JNR), Kawasaki Heavy Industries, Mitsubishi Heavy Industries, and several other manufacturers from 1930 to 1951.  The design of class D51 was based on the earlier D50 engine, introduced in 1923.  A total of 1,115 D51's were built, the largest number in any single class of locomotive in Japan.  
 
Early D51s were nicknamed Namekuji-gata ("slug-form") for their shape.  Designed by Hideo Shima (the engineer driving force behind Japan’s subsequent bullet train fleet, the D51  was used mainly in freight service through the 1960s.  Of note, 30 were left behind by the retreating Japanese military forces at the conclusion of the Second Sino-Japanese War (1937-1945), and the Soviets pressed these into service until 1979; Japan preserved 174 of these D51s, and five remain operational in contemporary times.
 
But back to the JNR; in 1906, the JNR – Kokuyū Tetsudō (state-owned railway, or Japanese Government Railways) – was founded by the Japanese Government via the nationalization of 17 private companies, with the Ministry of Railways and the Ministry of Transportation and Communications taking control of the network subsequently.
 
During WWII, many rail lines would be dismantled for their steel, in support of the war effort.  In mid-1949, by U.S. General Headquarters, Tokyo order, the JGR was reorganized into the JNR as s a public corporation.  The JNR would go from strength to strength in the years that followed, to include the inauguration of high-speed lines
 
The JNR was not state-run, and had independent accounting from the Japanese Government national budget.  It began to falter, however, in the early 1980’s, bogged down by rural sections without enough passengers to remain viable – the JNR would begin to close nearly 100 unprofitable local lines in 1983.  It wasn’t enough – by 1987, JNR’s debt was over ¥27 trillion ($442 billion at 2021 exchange rates).  The JNR would again be privatized in the late 1980’s and re-named the Japan Railways Group (or JR Group), with its remaining debt transferred to the national budget's general accounting. 
 
In modern times, JR Group has rid itself of the serious management inefficiencies, profit losses, and fraud that plagued the JNR - it runs over 20 thousand kilomters of tracks, and some bullet trains - the world's fastest - travel at rates nearly 400 km/h.  Seems like these bullet trains would make a great backdrop for a good film, no?  Maybe staring Brad Pitt, known for wearing other vintage Citizen?
 
This Limited Edition Citizen mechanical comes on its original Citizen-signed leather strap, and with a nylon strap, rugged travel case, and springbar tool.