Onsen Ichinoyu (Shinkotoni Branch)

This is a large day-use bathhouse in a Sapporo neighborhood, the kind of place locals drop into after work or on a day off. The baths run natural hot-spring water, including the cold plunge, and there's a real range of them: an indoor main bath, a jet bath, an electric bath, a deep cold bath, three individual tsubo-yu tubs, and outdoor bathing in both a hinoki-wood tub and a natural-stone rotenburo. Two saunas of different temperatures sit off the main bathing area. It draws a crowd, families especially, with a kids' corner and a light-meal and drinks counter for afterward. Reviewers describe it as lively rather than quiet: busy changing rooms, kids splashing around, people chatting in the baths. If you want a soak by yourself this isn't it, but as a straightforward neighborhood onsen sento it holds up.