Kagusa hot spring
Hot Spring Overview
Kagusa Onsen (Kagusa Hot Spring) is a secluded hot spring located deep in the mountains of Mt. Shirane in Kusatsu Town, Agatsuma District, Gunma Prefecture. It is not a typical hot spring facility but exists as a natural wild spring (gensen). Located away from the central Kusatsu Onsen resort area, it can be reached by taking a hiking trail from Kusatsu toward Yogahara, then following the Osawa River upstream for about an hour to an area above a large waterfall known as a "hot spring paradise." In this area, hot water springs forth from various parts of the stream, offering a completely wild and natural hot spring experience. Among the several hot spring sources in Kusatsu, Kagusa Gensen is known for having particularly high acidity. While there seems to have been a period when a bathing fee was charged, it is now enjoyed by visitors as a secluded mountain hot spring. Proper hiking or mountaineering experience and appropriate equipment are necessary, as it is not a hot spring that can be casually visited.
Hot Spring Details
Practical Info
Visit Log
Bath Types
Facilities
Access Information
Access to Kagusa Onsen is not easy and requires serious hiking or mountaineering experience. From Kusatsu Onsen town, you need to drive to the base station of the Shirane Volcano Ropeway, then walk along the hiking trail (Shibu Pass Kusatsu Nature Trail) toward Yogahara. Along the way, you must leave the hiking trail and enter the Osawa River, following it upstream for about an hour. The route includes challenging areas and a large waterfall, where ropes have been installed to help climbers ascend the cliff on the left bank (right side when facing the waterfall). Beyond this waterfall is the area called "hot spring paradise," which is the Kagusa Onsen area. Proper equipment (stream trekking shoes, knowledge of rope work, etc.) and sufficient physical strength are necessary, making it dangerous for beginners to visit alone. Additionally, the area may be closed due to volcanic activity on Mt. Shirane, so it is important to check the latest information beforehand. Access via public transportation is virtually impossible, and it is necessary to drive from Kusatsu Onsen town to the access point.
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About Secluded Rating
Access (Difficulty to Reach)
Over 1 hour walk
Kagusa Onsen is classified as Level 5 "Ultra-Secluded" on the secluded hot spring scale. Access is extremely difficult, completely inaccessible by car, and requires following a stream for more than an hour after leaving the maintained hiking trail. Along the way, there is a large waterfall where climbers must use ropes to ascend a cliff. There are absolutely no facilities, and it exists as a completely wild open-air bath with no changing rooms or other amenities. Information about this hot spring is limited, making it a hidden gem known primarily among enthusiastic hot spring hunters and locals. Depending on the season and volcanic activity status of Mt. Shirane, there are risks of access routes disappearing or being closed to entry. There is also the risk of encountering wildlife, necessitating adequate preparation and experience. Kagusa Onsen is a place that lives up to the name "Ultra-Secluded," offering a hot spring experience that can truly be called an adventure, one that hot spring enthusiasts dream of visiting at least once.