The E3 series Shinkansen is another mini-Shinkansen after the 400 series. It starts operating from 1997, serving the Tōhoku Shinkansen, Akita Shinkansen,and Yamagata Shinkansen. The interesting part of this train is that same as 400 series, it has a relatively smaller body compare to the other Shinkansens, It was designed to be running on some of the upgraded old lines which wasn’t originally designed to fit trains as big as the Shinkansens. The mini-size of the train body have a nick name called “Mini-Shinkansen”.
Why do you think engineers need to design a mini-Shinkansen?
Jasper's Blog on Trains 