To replace aging diesel railcars built in the sixties in service with small third sector operators, JR West introduced the KiHa 120 in 1991. This is a small four-axle railcar with a total length of only 16.3 meters. Power comes from a Komatsu SA6D125H-1 six-cylinder diesel producing either 250 or 330 hp depending on variant. Both axles of one bogie are being powered via a hydraulic transmission. There are three variants called 120-0, 120-200 and 120-300, which differ mainly in the interior. A total of 89 railcars were built by 1996. One has been retired after an accident and the refurbishment of others started in 2017. 