Shiramizu no Yu is a day-use hot spring facility in the Shirakawa-go area, with indoor and outdoor baths for travellers who want a soak after walking the village or nearby mountain roads. It is practical rather than historic, but it fills a useful niche in a region where many baths are tied to overnight stays.
Bring a towel or check rental options before going, and allow time for the rural location rather than treating it as a quick stop in Ogimachi itself.