Sixteen 7-car sets (112 vehicles) including one Green car were delivered between 1980 and 1981 to Shin-Maebashi depot to replace ageing 165 series EMUs.

Compared with the earlier 185-0 series sets, these had cold-region specifications, including snow-resistant brakes, front-end horn covers, and were able to operate over the Usui Pass between Yokokawa and Karuizawa in conjunction with JNR Class EF63 electric locomotives.

Livery was white with a single green band running the length of each car below the windows.

[1] The 7-car "OM" sets based at Ōmiya were formed as follows prior to March 2013, with car 1 at the south (Ueno) end.

Externally, the sets were repainted in white with yellow/grey/red blocks intended to represent the Jōmō mountain range together with "EXPRESS 185" markings below the windows.

In September 2010, 7-car set OM03 was repainted into the Shōnan colour scheme of orange and green (never previously carried by this type) to recreate the appearance of the early 80 series EMUs, as part of the 50th anniversary celebrations of the Kusatsu limited express service scheduled for October of that year.

[5] In July 2011, 10-car Tamachi-based set A8 was repainted into the original Odoriko colour scheme of white with green diagonal stripes at Ōmiya Works.

[6] In June 2012, 5-car Tamachi-based set C1 was repainted into the original Odoriko colour scheme of white with green diagonal stripes at Ōmiya Works.

[7] In February 2012, 7-car set OM08 was repainted into the JNR colour scheme of beige and maroon (never previously carried by this type) at Ōmiya Works to recreate the appearance of the early 157 series EMUs used on Amagi services.

As of Summer 2024 two six-car units still remain operational for rail tours and other special services.