Nagano's Tenryu Gorge is revered for its beauty throughout the seasons, with pine, maple, and cherry trees coloring the area at different times of year. During winter, a special event adds some manmade beauty to complement the stunning natural scenery at the Tenryukyo Night Museum.
The night museum includes an array of illuminations, with over 50 light fixtures scattered across the Tenryukyo Gorge Park grounds. Admission tickets are required for this year's event, which can be arranged via the official website here.
Do note that the lighting time differs depending on the day of the week you visit. From Monday to Thursday the light up is from 19:00-21:00, on Fridays that extends to 19:00-21:30, and on Saturdays, Sundays, and holidays they run from 18:00-21:30.