Myojin no Yu (Oyata Onsen)

Whatever your ailment, it can probably be treated at Myoji no Yu, whose salty, iron-rich 'netsu no yu' (literally, hot waters) are believed to improve circulation and offer relief for neuralgia, muscle pain, sore joints, sensitivity to cold and just about any other complaint you care to mention. This potent spring water is split between two cypress-wood tubs – one hot, one tepid – while the outdoor rotenburo and other baths are topped up with the stuff that comes out of the tap. There are discounts for female bathers on Ladies Day every Tuesday, and entrance is reduced to ¥600 if you turn up early (10am-noon) or late (after 9pm).