hot spring

According to the “Iki no Kuni Tsuzuki Fudoki,” these hot springs are said to have been flowing for approximately 1,700 years, with a historical legend that Empress Jingū, on her return from the Three Kingdoms Campaign, discovered the self-flowing hot springs in this area.

There is also a legend that Empress Jingū used the hot springs for her postpartum recovery and the first bath of Emperor Ōjin, which has led to its popularity as a fertility hot spring. During the Edo period, it is said that the medicinal temple “Onsenzan Iōin” prospered when Tokugawa Ieyasu, and later Tokugawa Iemitsu, enshrined the Yakushi Nyorai as the guardian deity.

On March 23, 1971, it was designated as a “Kokumin Hoken Onsenchi” (National Health Hot Spring) by the Ministry of Health and Welfare (currently the Ministry of Health, Labour and Welfare). This designation recognizes it as a hot spring area that meets the conditions for promoting the health benefits of hot springs with the cooperation of medical professionals.

Among the designated “Kokumin Hoken Onsenchi,” this hot spring, Yutonotsuru Onsen in Kumamoto Prefecture, and Yufuin Onsen (including Yufuin Onsen, Yuhira Onsen, and Tsukahara Onsen) in Oita Prefecture are the only ones in Kyushu to have received this designation.

The hot springs have various bathing effects, including relief for neuralgia, rheumatism, gynecological conditions, skin diseases, burns, and cuts. The high heat retention of the hot springs allows for better absorption of iron through the skin, which can be effective for conditions such as iron-deficiency anemia.

The analysis of the hot springs shows that the positive ion components, particularly sodium ions, are abundant along with magnesium and calcium ions. These components have a calming effect that can help alleviate cramps and inflammation. Additionally, the lithium ion concentration in the hot springs is more than seven times the standard level, which is known to have a calming effect and promote cellular activation, providing a soothing effect for fatigue.

The negative ion components, primarily chloride ions, are also present along with bicarbonate ions (which are characteristic of bicarbonate springs, also known as baking soda springs, and contribute to smooth skin). The bicarbonate ion concentration is 1.7 times the standard level, and the metaboric acid concentration is more than three times the standard level. Both components help dissolve excess sebum, leaving the skin feeling refreshed after bathing.