A Crimson Carpet in Early Summer
The Japanese azalea found at Yunomaru is scientifically known as Rhododendron japonicum. This deciduous shrub is native to Japan and typically prefers open, sunny grasslands.
When the flowers reach their peak, the rounded slopes of Mount Yunomaru appear to be covered by a vast crimson carpet. The vivid flowers stand out dramatically against the clear blue summer sky and the broad green highland landscape.
Ttsutsuji-daira Azalea Fields
One of the best areas for viewing the flowers is around the First Ski Slope and Tsutsuji-daira, a flowering area reached by taking the summer lift uphill.
Here, visitors can walk among the azaleas and observe the flowers at close range. During the flowering season and associated festival period, the summer lift operates, allowing visitors who prefer not to make a long uphill walk to reach the main viewing areas more easily.
Yunomaru Highland Azalea Festival
When the Japanese azaleas are usually at their peak, the Yunomaru Highland Azalea Festival is held on the fourth Sunday of June.
The festival takes place in conjunction with the opening of the summer mountain season at Kazawa Highland. Local specialties are sold, and visitors can enjoy activities such as prize drawings, traditional taiko drum performances, and jazz concerts.
The event offers more than an opportunity to see the flowers. It also provides visitors with a chance to experience the local community and enjoy the lively atmosphere of the highlands during the short summer season.
How Grazing Helped Create the Azalea Colony
The enormous Japanese azalea colony is not simply the result of natural chance. Its development is closely connected to the history of livestock grazing in the Yunomaru Highlands.
In 1904, the area began to be used as a summer pasture known as Yunomaru Ranch. From June through September, cattle and horses were brought to the highlands to graze on the grass. At its peak, approximately 300 to 400 animals were kept in the pasture.
A Unique Relationship Between Plants and Livestock
Japanese azaleas contain toxic compounds, including grayanotoxins, and grazing animals naturally tend to avoid eating them.
As cattle and horses fed on other grasses and plants, the Japanese azaleas were left largely untouched. Over many years, this helped the azaleas spread and form an exceptionally large colony resembling a natural woodland of azaleas.
The landscape is therefore an unusual example of how human economic activity and plant ecology interacted to shape a valuable natural environment.
Without grazing, taller trees and shrubs could gradually become more dominant, creating greater shade and potentially reducing the habitat suitable for Japanese azaleas. The present landscape reflects a delicate balance that has developed between nature and traditional land use.
Natural Monument Designation and Conservation
Japanese azalea is also the official flower of Gunma Prefecture and is widely associated with the region.
The Yunomaru colony was particularly valued for its enormous scale, high elevation, and scientific importance. Through efforts by Tsumagoi Village, it was designated a National Natural Monument in 1956.
From the 1960s onward, however, development such as ski-area construction and road improvements changed parts of the surrounding environment. Facility development has therefore been carried out under regulations governing changes to designated natural-monument areas.
Maintaining the Highland Habitat
The decline of traditional livestock farming has also reduced the number of grazing animals in the area. As a result, maintaining the open environment needed by the Japanese azaleas has become an important conservation challenge.
Today, the Yunomaru Japanese Azalea Conservation Association works together with local residents, government agencies, environmental authorities, and local high school students to protect the colony.
Conservation work includes removing taller trees and controlling bamboo grass and other vegetation that can compete with the azaleas.
These efforts demonstrate that the site is more than a famous flower-viewing destination. It is also an example of long-term landscape management and biodiversity conservation.
Subtle Differences From Plant to Plant
Not every Japanese azalea in the colony looks exactly the same. Although the flowers generally share their characteristic crimson color, individual plants can display subtle differences in tone, ranging from deep red to shades with a slightly more orange appearance.
The number of flowers also varies from plant to plant. These differences are valuable from a scientific perspective and provide an additional reason to slow down and observe the plants carefully while walking through the colony.
Access to the Yunomaru Japanese Azalea Colony
The site is located at 1053-40 Yunomaru, Kambara, Tsumagoi Village, Agatsuma District, Gunma Prefecture.
There is currently no regular public transportation service operating throughout the year. During the flowering season and festival period, however, a free shuttle bus from Manza-Kazawaguchi Station on the JR Agatsuma Line may be available.
By Car
By car, the area is approximately 20 minutes from the Tobu-Yunomaru Interchange on the Joshin’etsu Expressway.
From the Shibukawa-Ikaho Interchange on the Kan-Etsu Expressway, the journey takes approximately 120 minutes via National Route 144.
Because seasonal transportation services and road conditions can vary, visitors should check the latest local information before traveling.
A Landscape Shaped by Nature and Human Life
Yunomaru Japanese Azalea Colony is more than a spectacular flower-viewing destination. Its landscape reflects the long interaction between the natural environment and the people who have used these highlands for generations.
The colorful azaleas, open grasslands, mountain terrain, and traditional grazing history together create a distinctive cultural and natural landscape.
Experience the Crimson Highlands of Early Summer
In June, the refreshing mountain air of Yunomaru accompanies a remarkable panorama of crimson flowers covering the highland slopes.
The contrast between the brilliant azaleas, deep blue sky, and expansive mountain scenery creates an unforgettable summer landscape in Gunma.
A visit also offers an opportunity to discover the fascinating relationship between volcanic highland environments, traditional land use, biodiversity, and local conservation. Take time to walk through the area and experience this remarkable landscape at the foot of Mount Yunomaru.