JR East announced two days ago (JST) a new shinkansen/art gallery combination (?), the "Genbi Shinkansen" (現美新幹線), to run on the Jōetsu Shinkansen (Echigo-Yuzawa to Niigata) from spring 2016.
It's to be based on a 6-car E3 set seating ~105 total, fitted with art exhibition spaces in each car and a cafe in the third car. The exterior will have photographs of Niigata's Nagaoka fireworks festival. Apparently the new train has something to do with the Echigo-Tsumari art festival.
I know little of Japanese and less of art, so find more detailed information more directly from sources below:
RocketNews24: [1]
JR East press release (Japanese, PDF): [2]