I don't remember the name of the toyline but there are a lot of these out there - a boxy commuter train that can go inside out to reveal a Shinkansen or even a steam engine.
Ahh, the Hokutosei. They retired it a few years ago unfortunately. Believe it was due to raising the voltage through the Seikan Tunnel to make way for the Hokkaido Shinkansen
Any copyright or other distinguishing marks on the bottom?