I went on a trip to Kusatsu(草津) Onsen with some friends!
Onsens are popular destination for a day trip. Kusatsu is one of the popular onsens close to Tokyo (2-3 hr drive). We arrived there kinda late, but we got to enjoy the onsen, good food, and beautiful night view with steam and lights!
Definitely recommend onsen trips if you have a ride to get out of the city!