Yunomine Onsen Public Bath Kusuriyu

Yunomine Onsen rises in a narrow valley west of Kumano Hongu Taisha in Hongu, Tanabe City, Wakayama Prefecture. Said to have been discovered some 1,800 years ago, it is regarded as one of Japan's oldest hot spring settlements and is designated a National Health Resort Hot Spring. For centuries it served as the ritual bathing place where pilgrims on the Kumano Kodo purified themselves. At the center of the village stands the municipally run Yunomine Onsen Public Bath. The building closed in August 2020 for reconstruction and reopened on 23 April 2022 as a single-story structure of reinforced concrete and timber, roughly 250 square meters in floor area and finished generously in Kishu cedar and cypress. Inside it is divided into the general bath, the Kusuriyu, and a family bath, and the World Heritage Tsuboyu is managed and ticketed from the same counter.

According to the notice posted in the bathhouse, the water is a sodium bicarbonate and chloride spring with a source temperature of 74.5 degrees Celsius and a pH of 7.9, making it mildly alkaline and high in temperature. Kusuriyu takes the source water with no cold water added at all, cooling it naturally through piping before it enters the tub, so the bath is one hundred percent undiluted spring water. It runs nearly colorless with a faint milky cast, carrying a distinct scent of sulfur and flakes of white mineral bloom. Neither heating nor recirculation is used, though as a public bathhouse it discloses the use of chlorine-based disinfectant. The general bath, by contrast, dilutes the roughly 90-degree source with cold water and holds two tubs set to about 43 and about 40 degrees. That difference in dilution is what separates Kusuriyu from the general bath.

Kusuriyu consists solely of indoor tubs separated by gender, each large enough for five or six bathers. There are no showers or taps and soap may not be used, as the room is for soaking only; washing facilities, including four shower stalls with shampoo and body soap, are on the general bath side. The changing room has lockable lockers. Admission is 600 yen for those aged 12 and over and 300 yen for children under 12, with a day pass at 800 and 400 yen and a twelve-visit book at 5,000 and 2,500 yen. The bath is open from 6:00 to 21:00, with final admission at 20:30, and operates year-round apart from occasional closures in summer and winter for cleaning of the spring source. The ticket machine accepts QR code payments. Holders of a Tsuboyu ticket may also bathe once in either the general bath or Kusuriyu by asking the attendant.