Guida
Oike Yusui-gun is a group of natural springs located in Aso no, Shonai-machi, Yufu City, in the central-southern part of Oita Prefecture. It has been officially selected as one of the 'Top 100 Best Waters' by the Ministry of the Environment, a testament to its exceptional water quality. The water originates from the Oike spring (at an altitude of 850m) at the eastern foot of the Kuju mountain range, serving as one of the headwaters for the Aso-no River in the Oita River system. Situated within the Aso Kuju National Park, the area features well-maintained walking paths for visitors to enjoy.
The water flowing from this site has been used by local residents for centuries for daily life and agricultural purposes. As water travels deep beneath Mount Kuro, it undergoes a long filtration process through geological layers lasting months or even years. This process results in water that is naturally rich in minerals such as calcium. In recent years, due to its high quality, the water has even been marketed as premium mineral water, remaining a deeply rooted natural resource for the local community.
The greatest attraction is the sight of the pure, continuous flow of water. The water is classified as a calcium bicarbonate type with a hardness of 107.57 mg/L (soft water). The water temperature remains stable at approximately 12.6°C throughout the year, providing a refreshing sensation. With a daily discharge volume of approximately 20,000 tons, the site offers a powerful display of nature's vitality. Visitors can explore the area via established walking paths, allowing for a close encounter with the environment while preserving its natural state.
Oike Yusui-gun is accessible 24 hours a day, making it possible to witness the spring's beauty at any time. The scenery is beautiful in every season, but it is particularly striking during periods of lush vegetation when the spring is surrounded by vibrant greenery. For the best experience, visiting during daylight hours is recommended, as it is easier to navigate the walking paths and appreciate the surrounding topography and the movement of the water.
Here, you can witness the mechanism of natural spring water up close. A highlight is feeling the cool temperature and seeing the strength of the water as it emerges from the earth. The well-maintained trails allow for a peaceful stroll through the natural environment to observe the local terrain. For a more comprehensive water-themed itinerary, you can also visit Hakusui Kosen (located approximately 2km east), which is famous for its natural sparkling mineral water.
Located about 2km east of Oike Yusui-gun is Hakusui Kosen, known for its natural carbonated spring water. Since this area is part of the Aso Kuju National Park, visitors can enjoy vast, breathtaking landscapes of untouched nature. The natural environment of Shonai-machi in Yufu City is widely recognized as a place where one can experience the quintessential, original scenery of rural Japan.
While there are walking paths, the terrain is a natural environment. Please wear comfortable, active clothing and sturdy walking shoes (such as sneakers or hiking shoes). As the spring area is a public natural site, please observe proper etiquette, such as taking all your trash home with you to protect the environment. For any specific facility usage or related payments, please check local conditions on-site.