Soshigaya Onsen 21

If you’re a night owl, this sento that uses hot spring water is for you—it stays open till 2 am. Take a dip in the mini pool after warming up in the sauna for a refreshing session. This is a good place to take friends to chill after a drink. Tattoos are not allowed. There’s even a frozen sauna, a small room kept below freezing that you can alternate with the regular sauna. It’s very popular in the summer.