[2] In Hokkaido, where the proportion of electrified sections on trunk lines is low, the Class DD51 had been the mainstay of freight transport since the introduction of "smokeless railways", regardless of whether they ran on electrified or non-electrified sections.

After the creation of JR, the increase in freight transportation and the increasing speed of freight trains made the DD51's traction capacity insufficient, requiring trains to run with double heading.

Due to the harsh climate in Hokkaido, the cars also became increasingly obsolete.

[1] Batch built from August 2005 to December 2011 with IGBT VVVF inverters.

[6] In 2016, DF200-123 was moved from Hokkaido to Suita Depot in Osaka,[7] where it underwent modifications and renumbering to DF200-223 before being returned to service on the Kansai Main Line in the Nagoya area.