The Shiraito Falls are located in Karuizawa on the Nagano side. Karuizawa straddles both Nagano and Gunma prefectures. The falls are lit up during select periods in winter. The first of those illumination periods is called the "Christmas session". This year's Christmas session runs on December 17 and 18th, and from December 23rd to 25th.
After the Christmas Session, there will be a New Year Session and a Valentine's Day Session.
Please note, there are no buses running to this event. They request that you come by car or taxi. Also, while the attraction and the event are free, you have to pay a charge for using the Shiraito Highland Way toll road. The Shiraito Highland Way is a scenic route through a lush forest. It connects old Karuizawa with Mount Asama. The featured photo is one segment of the road during daytime hours.