Keiunkan is registered in the Guinness World Records as "the world's oldest hot spring inn." It was founded in 705 AD, which corresponds to the Keiun era, the fifth era after the Taika era. The inn's name is also derived from the era. Perhaps it would be more accurate to say that it was founded five years before the relocation of the capital to Heijo-kyo and fifteen years before the compilation of the Kojiki. The current innkeeper is the 53rd generation.
To connect its long and rich history to the future and achieve further evolution, Keiunkan underwent a major renovation. On March 5, 2026, it reopened as a newly renovated inn. The lobby, in particular, underwent a dramatic transformation. Although it was renovated when the inn started as a tourist ryokan in 1997, it has been remodeled with a calm atmosphere based on brown tones, transforming it into a modern space with a tranquil ambiance befitting the world's oldest hot spring inn.

Also newly established is the historical archives room, "Keiun no Kachiji." Kachiji is an old word meaning "a journey on foot," and the room displays numerous materials spanning over 1,300 years of the Keiunkan's history.
Part of its appeal lies in "the power of the continuously flowing hot springs that nurtured the hot spring therapy culture." In the second year of Keiun, Fujiwara no Mahito's twin sons, Shiro Nagamaro and Rokuro Jumaro, discovered boiling hot water vigorously gushing from between the rocks on the banks of the Yukawa River while hunting. They had a path carved into the rugged mountains and a hot spring pool built, which is the origin of Nishiyama Onsen. Afterwards, word spread that "there is a hidden gem of a hot spring nearby," and it eventually became a place for people suffering from illness to heal. During the Tenpyo era, when the 46th Emperor Koken moved to Yoshino due to illness, the miraculous spring of this mountain appeared to her in a dream. She traveled all the way from Kyoto with 80 attendants to Keiunkan for treatment, and is said to have recovered completely in just over 20 days.
The history of this secluded hot spring, nestled deep in the mountains of Kai, continues quietly... We encourage you to take your time and explore the history of Keiunkan, a world-class inn. This valuable museum allows you to feel the passion with which Keiunkan has carefully preserved the unique blessing of the land: the hot springs.

These four natural springs, nurtured over time beneath the Fossa Magna (Great Rift Valley) that divides the Japanese archipelago from east to west, are renowned springs that were beloved by figures such as Shingen Takeda and Tokugawa Ieyasu during the Sengoku period.
As a commemorative project for the 1,300th anniversary of the opening of the hot spring, the inn drilled for a new spring and struck a naturally flowing spring with a temperature of 52 degrees Celsius and a flow rate of over 1,600 liters per minute (approximately 8 drums), making it one of the largest in Japan. Combined with the four existing springs, the total flow rate reaches approximately 1,800 liters per minute. At Keiunkan, this abundant hot spring water is used in all the baths within the inn, as well as in the private baths in the rooms, for hot water supply, and showers, without any added water or heating. The water is colorless and transparent, highly alkaline, and has excellent skin-beautifying effects. Drinking the spring water is also said to be effective for digestive diseases and diabetes.
The open-air bath "Bokei no Yu" allows you to enjoy the sacred spring water amidst the magnificent nature of the Hayakawa and Yukawa Valleys. The long-loved cypress wood tub has been replaced with a cypress wood bathtub. In addition, a sauna and cold plunge pool have been installed, transforming it into a "relaxing open-air bath with a view" where you can enjoy the breeze blowing across the valley as an outdoor bath.
Furthermore, the "Keiryu Notenburo Hakuhō no Yu" stone bath, where you can enjoy the atmosphere of a deep mountain valley while soaking in a riverside hot spring, recreates the "cave bath" from the days of therapeutic hot springs. A "rock bath" made of Amahata inkstone from the Hayakawa River basin has also been newly installed.
The bathing facilities include the "Hinoki-ka no Yu" panoramic bath, which is filled with the fragrance of ancient cypress trees that have been rooted for over 2,000 years, the "Ishikaze no Yu" stone bath, and the private open-air stone baths "Kawaoto" and "Seoto" surrounded by the gentle murmur of the Hayakawa River, offering a truly timeless bathing experience.