Sekiyo. Another option is Okuyugawara Yui, an 11-room ryokan that is away from the center of town but is wonderfully secluded and has outstanding in-room Onsen, many with views of the river below. Even the entry-level rooms have a generous 100 square meters of space.

Other good choices are Zuigetsu and Miwa Yugawara - the latter serves Japanese-Italian cuisine.

For such a tiny little Onsen outpost, Yugawara definitely punches above its weight when it comes to high quality Onsen ryokans.