If you only have one or two days to spend, people will normally go to the onsen towns close to Tokyo such as Hakone, Atami, Syuzenji, and Ito. It will be a long drive to visit Kusatsu by car because it is situated on the mountain far from Tokyo. However, if you take a Kusatsu train that leaves from Ueno station, you can get there in 3 hours, 2.5 hours on the train and 30 minutes on the bus. I recommend that you book a reserved seat, and if you can afford to pay extra then book a seat in the Green Car compartment to have a comfortable and spacey seat.
In Kusatsu, there is a zoo to see and feed monkeys. There are public outdoor hot spring bathes overlooking the mountains and trees. In the winter it is surrounded by snow.
We stayed at a hotel called Kane Midori. Small but conveniently located near the tourist village and their service was beyond our expectation. When you check in, ladies can pick the kimono robe and colour of the belt from their selections. Gentlemen pick the size of kimono robe (small to extra large). When you are escorted to your room, nice Yuzu citrus tea and confectionary are served for you to relax. They also have a green tea set for you to be able to make tea while you are staying. Each guest will receive an Onsen Bag and there is a wash cloth and a tooth brush in it. The colour of the print of the name of the hotel on the towel match the colour of your bag. You can take it home after you use it. When you open the closet in your room you will find jackets to wear over your kimono when you go outside for a walk or walk around inside of the hotel. You will also see packages of Japanese style socks which you can bring home. You normally dine in at their beautiful authentic restaurant on the first floor but if you ask them in advance you can dine in your own room which we did for both dinner and breakfast. They have indoor and outdoor beautiful hot spring public bathes in the building but you can also book your own private bath for 3000 yen per 45 minutes which we did.
Outside of the public bath, there are massage chairs and free drinking water prepared.
Ahha, what a relaxing and pampered time we had and we would like to definitely go back.