Originally used to haul freight trains, they are now used primarily on track maintenance trains and rolling stock transfer duties. As of 1 April 2014[update], all four locomotives are in service. Locomotives 601 and 602 are normally based at Inuyama Depot, and 603 and 604 are normally based at Shinkawa Depot.
The four locomotives were built by Toshiba between 1943 and 1945.
Locomotives DeKi 603 and 604 were originally built as locomotive numbers E401 and E402 for use on the Japanese-occupied island of Hainan during World War II, but were ultimately not able to be shipped abroad, and were instead purchased by Meitetsu.
Originally painted in black with yellow and black chevrons at the ends, the locomotives were repainted into "Meitetsu Blue" when they underwent life extension refurbishment in 1992.