It was revealed by JR East on Dec. 2 that the new luxury suite train "Shikishima", scheduled to begin operation in the spring of 2017, will operate on one cruise plan through the Seikan Tunnel to Noboribetsu/Lake Toya in Hokkaido. The four day plan departs Ueno Station, goes to Nikko, then proceeds north on the Tohoku Main Line to Hokkaido. The return course takes the Sea of Japan side route, and transits Niigata Prefecture and the Joetsu Line to reach Ueno. The train will be capable of running under 25kV AC lines as well as 20kV AC and 1500V DC, as well as on non-electrified lines using its hybrid diesel setup.
http://trafficnews.jp/post/46466/
official website:
http://www.jreast.co.jp/shiki-shima/