Tadami Line was a short local line located north of Tokyo. The area of this line is quite mountainous and has heavy snow fall in winter. Logging was the main industry of the area. The Tadami Line was connected with Aize Line in 1971. The Tadami Line survived in streamlining of local lines. The snow fall in the area was so heavy and no road transport was available in winter. Only Tadami Line was the life line for the locals. The photos may include Tadami and Aize Lines. I do not remember location of the photos.
The locos in service were JNR C11 class.

今、地図を見て考えてみると当時の只見線だけではなく会津線でも撮っていたんじゃないかと思われます。記憶が飛んでいて思い出せない。重連なんかは会津線なんじゃないかなー。

JNR C11 Class

This class was a sort of all mighty tank engine made for short local lines, rapid suburban service, switchers in 1932. They were most popular modern tank engines in JNR.