Sentetsu Pashishi-class locomotive

Based on the experiences gained through the rebuilding of the Pureshi-class engines, the Pashishi class was, together with the Mikasa and Tehoro classes developed simultaneously, the first steam locomotive designed in-house by Sentetsu. Designed specifically for Korean operational conditions and needs, it proved to be very easy to build, operate and maintain, as care was taken during the design process to maximise the interchangeability of parts between the three classes.[2]

The Pashishi class were superheated two-cylinder locomotives intended for use on high-value passenger trains, of which a total of 82 were built for Sentetsu and for the Central China Railway by Kawasaki and Nippon Sharyō between 1927 and 1943.[2] From their inception, the Mikasa, Pashishi and Tehoro classes were designed to use the lignite abundant in Korea, which is less efficient than the anthracite the American-built locomotives needed; as such, they all had large heating areas. The Pashishi class featured a conical boiler and a combustion chamber firebox to achieve sufficient combustion of the coal, which in turn significantly improved evaporation and maintenance of steam.[2] The experience with these three classes induced the Japanese Government Railways to install combustion chamber fireboxes on the 9700 and D52 classes built for the JGR from 1943.

A state-of-the-art locomotive in its time, structurally it is generally an American design in its features, with the first dome being a sandbox, and the second being for steam. The firebox is located above the trailing axle. After the first four were completed, the design was modified, resulting in a slightly different appearance of the smokestack and the steam dome, and smoke deflectors were added. The tender is a four-axle type, running on two four-wheel bogies of American Bettendorf design. Four units, numbers パシシ981–パシシ984, were built in 1936 with partial streamlining, featuring a shroud on top of the boiler from the chimney to the cab, giving an appearance similar to the JNR's D51 22–23 locomotives. Further, they had a fully enclosed cab, a headlamp mounted at the centre of the smokebox door, and the idler wheels and tender wheels had roller bearings.[2]

After the defeat of Japan and the Liberation of Korea and of China, these locomotives were taken over by the new national railway companies of North Korea, South Korea and China. The exact division of the Korean locomotives is uncertain, but roughly equal numbers of the 72 locomotives are believed to have gone to the Korean National Railroad in the South and the Korean State Railway in the North.[3]