We stayed at this cozy, clean and comfy inn in January 2012 with the entire family (2 kids & 3 adults). We stayed in a large tatami room split in two sections on the 3rd floor with great views of the Japan alps. The onsen is a pure traditional hot spring. The onsen at Sakamotonoyu is the only onsen in the area that is not diluted with hot water or reheated giving you a true onsen experience which is hard to find in Japan these days. The husband and wife running the ryokan are extremely friendly and accommodating and can also speak good English to recommend sites around town. The dinner was exceptional which was served in a private tatami room on the 1st floor; 7 courses of seasonal dishes presented beautifully and tasted great!
Highly recommend this place and I've stayed at quit a few ryokans in Japan and this place certainly ranks as one of the best.