Fuji Cave (Fujido) is a limestone cave located within Kawawa Nature Park in Ueno Village, Tano District, Gunma Prefecture. Designated as a natural monument of Gunma Prefecture, it is one of the village’s most remarkable natural attractions.
Together with Oinukiana Cave, also located in Ueno Village, Fuji Cave is regarded as one of Gunma’s two major limestone caves. With a total length of approximately 2.2 kilometers, it is one of the largest cave systems in the Kanto region and offers visitors the chance to experience an immense underground world formed by nature over countless years.
Fuji Cave extends for approximately 2.2 kilometers, making it one of the largest limestone caves in the Kanto region. The sightseeing route open to visitors is approximately 600 meters long and takes around 40 minutes to explore.
After entering the cave, visitors first travel through an approximately 120-meter artificial tunnel before reaching the natural underground world.
The route includes a remarkable vertical shaft known as “Kara-ana,” approximately 40 meters deep. Visitors climb a spiral staircase through this section before reaching the main cavern. This unusual vertical layout is rare among caves in Japan and gives Fuji Cave an especially dynamic character.
The temperature inside the cave remains at approximately 10–11°C throughout the year. It feels refreshingly cool in summer and relatively warm compared with the outside air in winter, creating a comfortable underground environment regardless of the season.
Inside Fuji Cave, stalactites, stalagmites, and other limestone formations have developed over immense periods of time, creating an otherworldly landscape. Several distinctive formations are particularly noteworthy.
Hi no Hashira is one of the largest stone pillars inside the cave, rising more than 3 meters high. Its impressive scale and appearance make it difficult to believe that it was formed entirely by natural processes.
Enma no Kongōzue is a stone pillar associated with a local tradition that says wishes will come true if visitors gently stroke it seven times while making a wish. The formation also evokes the cave’s long history as a place associated with religious ascetic practices.
The formation known as the “Five Hundred Arhats” consists of stalagmites standing in tiers. Their appearance resembles a gathering of Buddhist statues, giving this section of the cave a solemn and mysterious atmosphere.
The cave also features striking formations such as the “Five-Colored Clouds,” whose patterns are created by mineral deposits, and the vast “Great Ceiling,” which resembles an enormous underground cathedral.
Illuminated by carefully positioned lights, the stalactites and other formations reveal intricate colors and textures. These natural works of art offer a fascinating glimpse into the immense geological history of the Earth.
The history of Fuji Cave is said to date back approximately 1,200 years. At that time, the area was covered by primeval forest, and a small opening was discovered surrounded by monkeys. Because of this, it was originally known as “Kōshin no Ana,” or “Monkey Cave.”
Approximately 400 years ago, Anshū, the founder of Fujiwarayama Kichijōji Temple, is said to have successfully explored the cave. It was subsequently used as a place for religious training and ascetic practice. Around this time, it was renamed “Daifukujuketsu,” and various sections of the cave were given names associated with Buddhism.
About 200 years ago, an epidemic spread through the local area. Ekigan Shōnin, the sixth head priest of Kichijōji Temple, reportedly wrote Buddhist scriptures on stones and placed them inside the cave while praying for the epidemic to subside.
It is said that the cave was later renamed “Fuji Cave” with the hope that such disasters would never return. The cave’s name and its various formations therefore reflect not only its geological history but also centuries of local faith and tradition.
Although Fuji Cave has been explored and surveyed for many years, parts of the cave system remain unexplored. A new side passage was discovered as recently as 1992, demonstrating that the cave still holds areas that have yet to reveal all their secrets.
Its labyrinthine structure and the possibility of undiscovered spaces add another layer of mystery to Fuji Cave. For visitors, exploring the accessible sections offers a sense of entering a hidden world that has been shaped by nature over an extraordinarily long period of time.
Approximately 40 minutes for the 600-meter sightseeing route.
9:00 a.m.–4:30 p.m.
From December through mid-March, admission hours are generally 9:30 a.m.–3:00 p.m. Hours may change depending on weather conditions and sunset times.
Fuji Cave is surrounded by a variety of attractions where visitors can enjoy Ueno Village’s natural environment. The nearby Ueno Sky Bridge offers an exhilarating walk high above the valley, while Mahoba no Mori provides camping, barbecue facilities, accommodation, and other outdoor activities.
Visitors can also enjoy hot spring facilities such as Yamabikoso and Villa Seseragi. Combining a visit to Fuji Cave with these attractions makes it possible to experience the mountains, forests, and hot springs of Ueno Village over a full day or an overnight stay.
Oinukiana Cave is another major limestone cave in Ueno Village and is designated as a national natural monument of Japan. It was discovered in 1929 by a group of local young men.
For generations, local tradition told of a cave inhabited by yama-inu, or mountain dogs. It was customary to leave offerings during their breeding season and pray for the safety of livestock. This tradition became associated with the local belief in the protective “Oinu-sama”, or revered dogs, and is thought to have given the cave its name.
When the cave was discovered, numerous animal bones, including wolf bones, were found inside. These remains attracted attention as possible evidence connected to the area’s long-standing legends.
Oinukiana is a vertical limestone cave formed as groundwater gradually eroded the surrounding limestone. It extends approximately 300–450 meters and has a four-layer structure.
Different sections of the cave have been given names inspired by Japanese mythology, including “Takamagahara,” “Tokoyo no Kuni,” and “Ame no Yasukawara.”
After its discovery, some stalactites and animal bones were removed from the cave, resulting in damage to this valuable natural site. Today, the entrance is kept locked and Oinukiana Cave is not open to the general public.
The cave is carefully protected and managed by Ueno Village so that its geological and historical value can be preserved for the future.
Fuji Cave and Oinukiana Cave have different histories, religious traditions, and geological structures, yet both represent important natural heritage created by the mountains of Ueno Village.
The mysterious underground landscapes reveal the immense passage of geological time and demonstrate the extraordinary power of natural processes. A visit to Fuji Cave offers travelers an opportunity to step beneath the mountains and encounter a hidden world that has been slowly shaped over countless generations.