The original structure of this building, which was recorded in Edo Period records, consisted of a southerly facing ‘ichinoyu’ and a northerly facing ‘ninoyu’ in a building that was connected and thatched with cypress bark, remained unchanged until 1883. In 1884, the building was reconstructed in a more western style. It has undergone further reconstruction since then and remains today with an inscription that identifies it as Japan’s first holy spirit spring. It is the oldest hot spring in Japan after Dogo hot spring and Shirahama hot spring.