Just four hours from the big city of Tokyo is the small getaway town Kusatsu; located in the middle of nature and away from all the skyscrapers and clamor of the city.
There are two main ways to get there: by train or by JR bus. We chose to go by bus due to the fact that the price was lower. The ticket was just a total of 6,360 both ways, leaving Shinjuku Station and arriving at Kusatsu Bus Terminal.
On our arrival at Kusatsu, all the main hotels were walking distance from the station so there was no need to take a train, bus, or taxi to any of the main resorts.
After arriving, we walked to the yubatake (the hot water field symbol of Kusatsu). It's a good idea to walk around to see the color of the water and the many food and souvenir shops around the area.
There are a couple of restaurants, as well as snack stores, around so if you get hungry you can eat and just wander around.
Another of the main activities that people do in Kusatsu is soaking their feet in one of the several ashiyu (foot bath) located in the area. A good choice to relax after a long trip!
Staying in one of the many onsen resorts is a must here!
Nothing compares to taking a hot bath at one of the many onsens that hotels offer, wearing a yukata, and going to eat a freshly made dinner, which in my experience was a huge amount of fresh and healthy food.
After that, you can either relax for a while in your room or--what I recommend--go on a walk at night and admire the illumination of the yubatake. It's a completely different scene than from the daytime view and totally worth it.
To summarize, if you like onsens or want to try them, then going to Kusatsu is the best choice. There are several bathhouses to choose from but staying at an onsen resort would be the ideal choice. Enjoying as many baths as you want and delicious traditional food of an onsen resort is a great experience to have outside of the usual big-city destinations.