The C61 steam locomotive was constructed with a boiler and other spare parts from the D51 steam locomotive to meet the rapid increase in passenger travel after World War II. Incorporating the large C57 chassis, it is used primarily for passenger travel.

The axle configuration is made up of two sets of leading wheels, three driving axes and two sets of driven wheels, known as the Hudson wheel arrangement or 2C2. The Hudson arrangement was first used in Japan on the C61. Between 1947 and 1949, 33 C61s were produced, and of those, the C61 20 has provided passenger service on the Tohoku Main, Joban and Ou Main Lines, and was also employed on the Hatsukari, which was the first limited express in the Tohoku area, and between Sendai and Aomori on the Hakutsuru, a sleeper limited express.

Then in August 1973, the C61 20 was pulled out of service. The following January, it pulled into Kezoji Park in Isesaki, a city in Gunma Prefecture, where it was put on display after reassembly and polishing. With the aim of teaching the next generation about the railway heritage of steam locomotives, the C61 20 underwent restoration work in 2010 and received a new operation registration in March 2011. Since then, it has operated mainly for special events on the Joetsu and Shinetsu Lines.