Karuizawa station is the main station of Karuizawa, a town located in eastern Nagano prefecture. Karuizawa is one of the most popular tourist destinations in Nagano and one of the famous hill stations in Japan, which attracts thousands of tourists daily in summer. Holiday cottages of wealthy Japanese are located in Karuizawa too.
Karuizawa was developed by Seibu group, which is leaded by Seibu railway and Prince hotel. It hosted Equestrian at the Tokyo Summer Olympic games in 1964 and curling at the Nagano Winter Olympic games in 1998, which made Karuizawa to be the first municipality to have both summer and winter venues.
Karuizawa station was a station for JR's Shin'etsu main line till September 1997 but the section between Yokokawa station in Gunma prefecture and Shinonoi station in Nagano prefecture, including Karuizawa station was removed from JR East when Nagano Shinkansen(current Hokuriku Shinkansen) was opened. This section was ceded to Shnano Railway, a third-sector railway company.
Currently Japan Rail Pass holders can reach Karuizawa station by Hokuriku Shinkansen, mostly Asama trains from Tokyo. If you are traveling from Kyoto or Osaka, it is faster to go to Tokyo station by Tokaido Shinkansen and change to Hokuriku Shinkansen.