The Manchukuo National Railway was the state-owned national railway company of Manchukuo. Generally called the "國線", it was controlled by the Manchukuo Ministry of Transportation and had its lines primarily in the central and northern parts of the country. In local newspapers it was simply referred to as "國鉄". It was built, operated and managed by the South Manchuria Railway, a state-owned national railway company of the Empire of Japan, of which the Kwantung Army frequently intervened in its affairs.

The China Railways SL3 class steam locomotive was a class of 4-6-2 passenger steam locomotives operated by the China Railway. They were originally built for the South Manchuria Railway, the Manchukuo National Railway and the North China Transportation Company by several Japanese manufacturers between 1934 and 1940. They were designed in 1933 based on the design of the first Pashisa class locomotives ; the first order was placed by Mantetsu in March of that year.