Touted as the "only snow resort in the world with a shinkansen station", GALA Yuzawa is one of the most accessible ski resorts from Tokyo. It is easily reached via an hour ride on the Joetsu Shinkansen, with the bullet train station located within the resort premises. For those without rail passes, there are also multiple highway bus packages to go to GALA Yuzawa from Tokyo.
Ski season is dependent on each year's snowfall rate, its best to check in advance on the resort's opening hours.
Joetsu Shinkansen to GALA Yuzawa station