The 63 series was originally introduced in 1944 as a means of transporting increasing number of workers commuting to factories of arms and other industries.

The cars were designed under the overall goal of mass transportation amid the serious shortage of supply in the wartime.

Interior flooring was wood, luggage racks were installed, and seats were upholstered.

Worn-out bodies made the trains look ugly and the effects of short-circuit was shown in the Sakuragichō train fire that happened on the Keihin Line (now Negishi Line) on April 24, 1951, by which 92 people were injured and 106 were killed.

It was built in 1947 by Kawasaki Sharyo, and was later renumbered KuMoYa 90005 as a non-revenue earning car, before being stored at JR Central's Hamamatsu Works.