Guide
Oike Springs (Oike Yusuisun) is a beautiful spring group located in Aso no, Shonai Town, Yufu City, in the central-southern part of Oita Prefecture. It has been officially selected as one of the '100 Best Waters' by the Ministry of the Environment, a testament to its exceptional water quality. The water originates from the eastern foot of the Kuju Mountains at an altitude of 850m and serves as one of the headwaters for the Asono River in the Oita River system. Situated within the Aso Kuju National Park, the area features well-maintained walking paths for visitors.
Since ancient times, the water from this site has been vital to the local community, used for both daily life and agriculture. The water travels deep beneath Mt. Kurodake for months or even years before emerging, a process that naturally infuses it with an ideal balance of minerals like calcium. In recent years, due to its high quality, the water has even been marketed as premium mineral water, remaining a deeply cherished resource for the local region.
The primary draw is the sight of the pure, continuous flow of water. The water quality 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 of roughly 20,000 tons, the site offers a powerful display of nature's vitality. Visitors can explore the area via the surrounding walking paths, which are designed to allow for nature observation while preserving the environment.
Oike Springs is accessible 24 hours a day, 7 days a week, making it easy to visit at any time. You can observe the spring regardless of the season, though the scenery is particularly striking during seasons when the surrounding vegetation is lush and green. For the best experience, visiting during daylight hours is recommended, as it makes it easier to navigate the walking paths and appreciate the surrounding topography and the clarity of the water flow.
Here, you can witness the natural mechanism of spring water up close. You can feel the energy of the water surging from the earth and experience the refreshing coolness of the temperature. The established walking paths allow for a peaceful stroll to observe the local geology and flora. For a complete regional water-themed itinerary, you might consider visiting the nearby Hakusui Mineral Spring (approx. 2km east), which is famous for its natural carbonated water.
About 2km east of Oike Springs lies the Hakusui Mineral Spring, known for its natural carbonated water. As the springs are part of the Aso Kuju National Park, the entire area is surrounded by breathtaking natural landscapes. The environment of Shonai Town in Yufu City is widely recognized as a place where one can experience the quintessential, nostalgic scenery of rural Japan.
While there are walking paths, the terrain is a natural environment. Please wear comfortable clothing and sturdy walking shoes (such as sneakers). As this is a public natural site, please follow environmental etiquette: always take your trash home with you to protect the ecosystem. Regarding any nearby facilities that may require payment, please check local conditions upon arrival.