There are about 50 natural hot spring sources along the Kuma River in Hitoyoshi. Hitoyoshi is located in what was once a lake millions of years ago. Hitoyoshi is located within the Mt. Aso and Mt. Sakurjima volcano range. Magma from this volcano range heats underground water which springs above ground. This is the source of Hitoyoshi’s natural thermal hot springs. The depth of these hot springs ranges from about 150 meters deep to more than 500 meters underground. Some hot spring waters are colorless, odorless and alkaline.
Other hot spring waters contain carbonated sodium and hydrogen elements. Hitoyoshi’s hot springs are unique because they do not emit sulfurous smells nor clouds of steam. Temperatures range from about 40℃ to 50℃. It is well documented in an historic text written in 1492, that King Tametsugu (the 12th King of the Sagara Dynasty) bathed in Hitoyoshi’s natural hot springs. King Tametsugu had gone to the shrine to pray. On his way back to Hitoyoshi Castle, he stopped to bathe in a hot spring. He wrote a poem reflecting his impressions of the hot spring which was then documented by a royal scribe. About 100 years ago, the Hisatsu rail line and Kuma River boat rides began operations. Around this same time, Suiranro opened natural hot spring facilities for guests. Thanks to the great popularity of the Suiranro hot springs, other hot spring facilities were soon opened in many places within Hitoyoshi. When the city had established about 30 hot spring sources, it became known as Hitoyoshi Onsen area. Today, there are about 30 hot spring facilities open for bathing. Collectively, the waters are known as “beauty waters” due to the many skin benefits of bathing here.