Sentetsu Pashii-class locomotive

As the 1920s approached, it became clear that Sentetsu needed more powerful locomotives than its existing Amei-class and the five classes of Teho-type locomotives then in service to pull its important passenger trains. Consequently, Sentetsu turned to the Baldwin Locomotive Works once again, this time ordering passenger steam locomotives of the 4-6-2 wheel arrangement.^[2]

The first locomotives with a 4-6-2 wheel arrangement to operate on Korean rails was Sentetsu's パシイ (Pashii) class. This was a group of twelve locomotives built by Baldwin in the United States and delivered to Korea in 1921. They had a steel underframe, a hard link type front bogie and a spring type rear bogie, a Franklin injector, an automatic stoker, Gould regulator, and Westinghouse 6ET air brakes.^[2] Originally numbered パシ901–パシ918, they were the most American in appearance due to the arrangement of their running boards, and, like American locomotives, had the driver on the left hand side; this proved unpopular with the local crews, as they were the only left-side-drive locomotives in Korea until the arrival of the USATC S160 class after the end of the Pacific War.^[3] Despite this drawback, they were considered a success, and in 1923 six copies were delivered from Kisha Seizō.^[2] These moved the driver to the right side, and were originally numbered パシ919–パシ924. A year later, they swapped numbers with the Pashini class locomotives that had been delivered in 1923 before the Pashii copies, becoming パシ913–パシ918, and in Sentetsu's 1938 general renumbering, the eighteen locomotives were renumbered パシイ1–パシイ18.^[3]