The KiHa 40 family railcars were built in larger numbers between 1977 and 1982 to replace various older commuter diesel railcars. A total of 888 vehicles of the three series were built, which differed primarily in the number of driver's cabs and the design of the doors. The KiHa 40 was developed for lower passenger volumes and is usually used as a single vehicle. That's why it has two cabs and narrow doors directly behind the cabs. The KiHa 47 is used in pairs and therefore has only one cab per car and double doors that are slightly offset to the middle of the car. The KiHa 48 also has only one cab, but narrow doors.

In addition, the sub-classes of the vehicles are designed for different climatic conditions. In the vehicles for the very cold climate on Hokkaido, for example, the entrance areas are separated from the seating area, while the windows in the vehicles for warm climates can be opened more generously. Likewise, the vehicles for cold climates have air suspension and those for warm climates have coil springs. The engine is a horizontally arranged six-cylinder turbo diesel, which was derived from the twelve-cylinder boxer of the KiHa 66 and delivers 220 hp continuously and 250 hp for short periods.

After the privatization and division of the JNR, the vehicles were distributed to all of the six successor organizations. Originally JR Hokkaido got 157, JR East 219, JR Tokai 59, JR West 257, JR Shikoku 53 and JR Kyushu 142 vehicles. In 2018, 714 units were still in use, some of which had been modernized and rebuilt. Some vehicles received 300 or 350 hp Cummins engines. Some vehicles are used today as “joyful trains” for charter excursions in special paintwork or with special equipment.