Etajima-so is a resort hot spring inn located in Nakamachi, Nomicho, Etajima City, Hiroshima Prefecture, overlooking the Seto Inland Sea. Opened on July 1, 2021, it is a relatively new luxury facility selected for the 2025 Michelin Guide Hotel Selection. With 32 guest rooms and a total floor area of 3,573 square meters, it accommodates up to 128 guests. The source spring, Etajima Onsen, is classified as a weak radioactive sodium-calcium chloride strong salt spring, combining the characteristics of chloride and sulfate springs for double moisturizing and warming effects. The water contains over 14,600 mg of chloride ions per kg, approximately 26 times the legal hot spring standard. Among the rare radon-containing springs in Japan, its highlight is a precious low-temperature source of about 30 degrees Celsius enjoyed as flowing nuru-yu (lukewarm bath) without heating or dilution. Facilities include indoor baths, open-air baths, lying baths, mist sauna, and semi-open-air private baths.