There are 9 Shinkansen lines in Japan. Most popular one for foreign tourists is the oldest Tokaido Shinkansen, which commenced in 1964. Then, Sanyo and Hokuriku Shinkansen are popular for the tourists due to there are famous destinations as like Hiroshima and Kanazawa on the routes.
On the other hand, may be Joetsu Shinkansen is least popular Shinkansen for foreigners. Joetsu Shinkansen are connecting Tokyo and Niigata city. It is running through Tokyo, Saitama, Gunma and Niigata prefectures, total 333.9 km. Between Tokyo and Omiya stations are also operated by Tohoku Shinkansen, between Tokyo and Takasaki stations are also operated by Hokuriku Shinkansen. Therefore foreign tourists will use Joetsu Shinkansen in case they have to go to somewhere between Takasaki and Niigata or have to change at the stations on the way.
However, unfortunately there is no popular or famous tourist attractions on the way. Niigata city itself is more than 0.8 million inhabitants but one of the big cities in Japan which does not have any major tourist attractions. On the other hand, Niigata prefecture has a nice sake breweries, ski resorts and hot springs which are relatively close to Tokyo.
Then, trains of Joetsu Shinkansen are also different from other Shinkansen. Joetsu Shinkansen has the double-decker trains, E4 series trains. Compositions of the trains are either 8 or 16. Actually 16 cars are the longest composition for Shinkansen on single line.
E4 series debuted in 1997 and should be retired in 2020, replaced by E7 series which is currently running on Hokuriku Shinkansen. However, the seat capacity of E4 is 1634 but E7 has only 924, which means 710 people cannot get the seats in case the train is full. To prevent this unpleasant situation, JR East will run more trains frequently in the morning.
If you want to ride the double-decker Shinkansen, please visit Japan until 2019!