Hi, I see you are talking about the Aizu line - I am just curious about how night trains from Tokyo (Ueno) to Aizu-Wakamatsu worked in the 60s-70s. It was relatively a short distance even at that time, with day trains (using the same Tohoku Main Line) about 4 hours. So did night trains go slower deliberately? And night trains were even more popular for that route. I am curious. Thanks!
Sorry about the delay in replying! Unfortunately, I can't answer your question - my knowledge is pretty well restricted to the Aizu Line and the Tadami Line, and to a lesser extent, the Nitchuu Line. I know next to nothing about the long distance operations between Tokyo and Aizu-Wakamatsu. Sorry! :(