Mantenboshi no Yu is a day-use hot spring facility located in Sarugakyo Onsen, Minakami Town, Gunma Prefecture. Perched on a hill overlooking Lake Akaya, it is surrounded by a rich natural environment that is part of a UNESCO Biosphere Reserve.
The surrounding mountains change their appearance with the seasons, while the deep blue waters of Lake Akaya create a spectacular setting. The peaceful scenery provides visitors with a relaxing escape from the noise and stresses of everyday life.
The greatest attraction of Mantenboshi no Yu is the spectacular scenery from its outdoor baths. During the daytime, visitors can enjoy expansive views of Lake Akaya and the surrounding mountains while soaking in the open-air hot spring.
Each season offers a different landscape, from the fresh greenery of spring and the deep green forests of summer to the colorful autumn foliage and snowy winter scenery. The changing views make every visit a unique bathing experience.
After sunset, the atmosphere changes completely as the night sky fills with stars. On clear nights, countless stars spread across the sky and may be reflected on the surface of the bath, creating a wonderfully atmospheric experience.
The facility’s name, Mantenboshi, refers to a sky filled with countless stars. Enjoying a hot spring beneath a star-filled sky is one of the most memorable experiences offered here.
The facility has two bathing areas, Sato no Yu and Tanabata no Yu, which alternate between men and women each day.
Sato no Yu features a peaceful outdoor bath surrounded by a Japanese-style stone garden. It also has reclining baths where guests can relax while enjoying the tranquil surroundings.
The calm Japanese atmosphere makes this bath particularly suitable for visitors looking to slow down and enjoy a peaceful bathing experience.
Tanabata no Yu has a modern Western-style design featuring attractive stone surfaces. A jacuzzi is also available, providing another way to relax and refresh both body and mind.
Both bathing areas include a large communal bath, a warm-temperature bath, and a sauna, offering several ways to enjoy the hot spring.
The hot spring water is classified as a calcium-sodium sulfate spring. It is known for warming the body thoroughly and for helping guests remain warm after leaving the bath.
As the water is mildly alkaline, it is also said to soften the skin’s surface, leaving the skin feeling smooth and refreshed after bathing.
The hot spring has traditionally been used for relaxation and to ease various everyday physical discomforts, including muscle aches, joint discomfort, shoulder stiffness, sensitivity to cold, and fatigue.
The baths are also suitable for leisurely bathing, making them a pleasant choice for visitors who want to take their time and relax in the warm water.
Visitors seeking a more private experience can use the private hot spring baths. The tubs are made from natural wood, and the gentle fragrance of the wood creates an atmosphere reminiscent of relaxing in a forest.
The facility also offers relaxation services such as traditional Korean-style yomogi mushi herbal steam treatments and Chinese-style hand massage. Yomogi mushi involves relaxing in herbal steam and is particularly popular among visitors interested in traditional wellness experiences.
The on-site restaurant serves a variety of dishes prepared with ingredients from Gunma Prefecture. Popular choices include Joshu Mugibuta pork tonkatsu and ginger-fried pork set meals, featuring tender, flavorful local pork.
Other choices include fried Akagi chicken, handmade soba noodles, and the distinctive Aimata Dam Curry, inspired by the nearby dam.
The restaurant also offers views of Lake Akaya, allowing guests to enjoy the scenery while dining. Restaurant-only visits are also possible, making it a convenient place to stop during a scenic drive even without using the hot springs.
The facility has a spacious 110-tatami-mat hall that serves as a free relaxation area. It is a comfortable place for families and groups to rest after bathing or to take a break during their journey.
Private rooms are also available for those who prefer a more secluded space. The on-site shop sells fresh locally grown vegetables, regional specialties, souvenirs, and original products, making it a convenient place to find gifts and local foods.
Mantenboshi no Yu offers more than hot springs. Visitors can enjoy a variety of outdoor activities, including garden barbecues, kayaking, and trekking.
The facility also includes the cultural venue Dendekoza Mikunikan, where performances of popular theater and lectures are held. Other facilities offer traditional folktales and kamishibai picture-story shows, providing entertainment and cultural experiences for visitors of different generations.
Sarugakyo Onsen is a historic hot spring resort with a long tradition. According to local legend, a white-handed monkey once brought healing to people in the area, and this story is associated with the origins of the hot spring.
The present-day hot spring resort was relocated during the construction of Aimata Dam, but its abundant hot spring water and distinctive mineral qualities have continued to attract visitors.
Hotels, traditional Japanese inns, and other tourist facilities can be found throughout the surrounding area, giving Sarugakyo the atmosphere of a traditional hot spring resort. The combination of history, nature, and hot spring culture makes it an appealing destination for a relaxing getaway.
Mantenboshi no Yu brings together hot springs, nature, local food, cultural experiences, and the welcoming atmosphere of a traditional resort destination.
Relaxing in a hot spring while looking across Lake Akaya, surrounded by changing seasonal scenery, offers a peaceful experience far removed from the bustle of everyday life.
For travelers looking to unwind in a beautiful natural setting, Mantenboshi no Yu provides an opportunity to experience the relaxing side of Minakami and the traditional hot spring culture of Sarugakyo Onsen.