Yumura Onsen is the heart of Shinonsen, a compact hot-spring town built around the Arayu source. The water is famously hot, and the public basins for boiling eggs and vegetables turn the spring into part of daily street life rather than a hidden bathhouse amenity.
Foot baths line the river, ryokan cluster close to the steam, and the town is best seen slowly. Come late in the day, when the lanterns and vapour soften the concrete edges.