Iwaiya is a historic ryokan located at 544 Iwai, Iwami-cho, Iwami District, Tottori Prefecture, situated in Iwai Onsen, known as the oldest hot spring in the Sanin region. Iwai Onsen has a history of approximately 1,200 years, said to have opened in 859 AD during the Heian period, and is counted as one of the eight ancient hot springs of that era. Iwaiya was founded in the late Edo period, and its current wooden three-story building was rebuilt after the great fire of 1934. With only 14-15 guest rooms, it offers a quiet and intimate atmosphere. As a member of the Japan Secret Hot Springs Association (Hitou wo Mamoru Kai), it is highly regarded by hot spring enthusiasts nationwide. The water quality is calcium-sodium sulfate spring (Glauber's salt-gypsum spring) with a source temperature of approximately 50 degrees Celsius. The bath uses 100% pure source water with no dilution, heating, circulation, or chlorination. The signature large bath, Gensen Choju-no-yu (Source of Longevity Bath), is a deep bath where bathers can immerse themselves up to the chest, with the spring water naturally bubbling up from beneath pine boards on the bath floor (ashimoto-yushutsu, foot-source emergence). Other facilities include the open-air bath Sedo-no-yu, indoor bath Iwai-no-yu, and private bath Yoimachi-gusa. The ryokan also preserves the unique traditional bathing custom of yukamuri.