I visited Shima Onsen twice while living in japan, and staying in the ryokan was one of the most relaxing experiences I’ve had. All the rooms are beautiful, the staff are so gracious, the food is amazing and the bathes are beautiful. This would be a wonderful trip any time of year, I especially loved visiting in winter when it was snowing! It was amazing to see the snowflakes falling while sitting in a hot onsen outside. The town is also easily accessible from Tokyo on the bus, and is such a different experience from the feel of the main cities in Japan. I hope I can visit again one day.