What Is Mt. Akagi?
Mt. Akagi (Akagiyama) is a complex volcano centered around Maebashi City in Gunma Prefecture, with broad foothills and 1,828 m Kurobi-san as its highest peak. It is one of the Three Mountains of Jōmō (Jōmō Sanzan).
In addition to Kurobi-san, the mountain group includes Komagatake, Jizō-dake, Arayama, Nabewariyama, Suzugatake, and Chōshichirōyama, and is recognized as one of Japan's 100 Famous Mountains as well as one of the Three Mountains of Jōmō.
Rather than thinking of Mt. Akagi as a single peak, it is easier to appreciate the area as a wide mountain region combining the caldera lake of Lake Onuma, the crater lake of Lake Konuma, the Kakumanbuchi wetland, and the surrounding outer rim mountains.
The central area is designated as Akagi Prefectural Park (about 1,290 hectares) by Gunma Prefecture, making it easy to enjoy the lakeside and wetland scenery without doing any serious mountain climbing.
Top Sights at Mt. Akagi: Lake Onuma and Kakumanbuchi
Lake Onuma: A Caldera Lake Perfect for an Easy Stroll
Lake Onuma (Onuma) is a caldera lake at an elevation of about 1,340-1,350 m, surrounded by primeval forest.
The lake covers about 880,000 square meters, has a circumference of around 4 km, and reaches a maximum depth of about 19 m. A circular road and walking path run around the lake, taking about 60 minutes to complete.
You can walk while enjoying scenic lakeside views typical of Mt. Akagi. The lake changes with the seasons and is also known for boating, camping, and pond smelt fishing.
Bringing your own canoe or kayak is allowed from June 1 to October 31, between 9:00 and 15:00. It's also one of the easiest places to experience Mt. Akagi's nature for those not confident about hiking.
Kakumanbuchi: Ideal for Quiet Nature Watching
Kakumanbuchi is a wetland of about 1 km in circumference at an elevation of around 1,360 m, located southeast of Lake Onuma. It is designated as an Important Wetland by the Ministry of the Environment.
Known as "Ko-Oze" (Little Oze) thanks to its wetland and alpine plants, Kakumanbuchi can be enjoyed via a wooden boardwalk that runs through the marsh.
Unlike the rugged terrain near the summit, Kakumanbuchi offers a slow, peaceful experience of open water and grasslands.
It's a great choice for photographers and travelers who prefer nature observation to mountain climbing.
Things to Do at Mt. Akagi: Choose Your Walk by Goal
Mt. Akagi offers a range of options, from light hiking to serious mountain climbing.
For a first visit, deciding in advance whether you want to walk along the lake or head up for mountain views makes it easier to plan.
The areas around Lake Onuma and Kakumanbuchi have minimal elevation gain, making it easy to enjoy Mt. Akagi's scenery on relatively gentle terrain.
On the other hand, climbing the outer rim mountains such as Kurobi-san or Jizō-dake reveals sweeping views down onto Lake Onuma, Lake Konuma, and Kakumanbuchi - giving the same Mt. Akagi a completely different feel.
How to Get to Mt. Akagi
To reach the summit area of Mt. Akagi, plan on about 1 hour to 1 hour 30 minutes by bus or car from JR Maebashi Station.
There are several parking lots around Lake Onuma and Kakumanbuchi, and it's about a 50-minute drive from the Akagi IC on the Kan-Etsu Expressway.
Best Time to Visit Mt. Akagi: Seasonal Highlights
Fresh Greenery to Early Summer
At Kakumanbuchi, the fresh greenery of late May through June and the orange-red Japanese azaleas (renge-tsutsuji) of mid- to late June are particularly well known.
When the wetland's plants soften into seasonal colors, it's an ideal time to combine boardwalk strolls with changing scenery.
In summer, alpine plants such as Nikkō daylilies (nikkō-kisuge) can also be observed from July through August.
Autumn to Winter
Autumn leaves around Lake Onuma and Kakumanbuchi peak from mid- to late October, when the contrast between the lake and the colored mountainsides is unforgettable.
From mid-December onward, Lake Onuma's frozen surface and snow-covered scenery create classic winter views of Mt. Akagi, and pond smelt fishing on the ice from January through March is a great way to experience the seasonal change.
Tips Before Your First Visit to Mt. Akagi
Mt. Akagi sits in a high-elevation natural environment above 1,300 m, so even a casual sightseeing visit calls for preparation suited to mountain conditions.
In particular, it's wise not to assume that sudden weather changes or road conditions will behave the same as in town.
- Check the weather: Pay close attention to weather forecasts and disaster information when hiking or visiting during the rainy season.
- Lake usage rules: Swimming is prohibited at Lake Akagi-Onuma under the lake-use guidelines, and bringing your own canoe or kayak is limited to June 1 - October 31.
- Winter gear: From mid-December to late April, prepare for icy roads and snowy trails with winter tires, anti-slip gear, and light crampons.
- Respect the environment: Kakumanbuchi is a precious wetland designated by the Ministry of the Environment. Stay on the boardwalk or marked trails and avoid damaging the plants.
- Bear awareness: Bears have been reported in Akagi Park, so traveling in groups and carrying a bell or radio is recommended.
Summary
Mt. Akagi isn't just a place to head for the summit - the lakeside of Lake Onuma, the wetland of Kakumanbuchi, and the views from the outer rim mountains all offer different ways to enjoy the area depending on where you walk.
If it's your first visit, start with the scenery of Mt. Akagi around Lake Onuma and Kakumanbuchi, and from there expand to climbing Kurobi-san or exploring the surroundings to find the way to enjoy Mt. Akagi that suits you best.
