Shinshu Fudo Onsen Sagiriso

The bath is simple, one indoor room with a single tub, a shallow step so small kids can wade in safely, and a big window over the Sai River. The water has a light sulfur edge and runs mild rather than hot, more of a nuruyu (ぬる湯) soak, and a few regulars come back specifically for that gentle, slow-warming feel. Sagiriso sits on Shinshu Shinmachi's Jingisukan Road (ジンギスカン街道), a valley stretch known for grilled lamb, and its own dining room serves mutton tableside alongside the stay. The spring is named for Fudo Myoo (不動明王), enshrined above its source at a waterfall upriver, and has been piped down to the inn for generations.