My friend and I rented a car and took an overnight trip to a cool place in the mountains in 群馬県 (Gunma Prefecture). We were nearing the end of summer but 東京 (Tokyo) but it was still super hot every day. Normally, 温泉 (onsen) are not big in the summer because its already hot. But because this was in the mountains, it was a much appreciated break from the heat. It was still t-shirt-at-night weather but much cooler than home.
Aside from weather, this place is just so cool. There is hot spring water through the wooden channels in the middle of the town. A long time ago, those were used for cooking food and other normal tasks. Now they’re just for tourists. And the hot water is not limited to there. Of course it feeds all of the onsens, but I also came across more than 1 hot river flowing through a park or down the mountain. Kusatsu is definitely a neat place.