The Origins and Expanding Area of Shiga Kogen
The name “Shiga Kogen” originated with Tohei Kozu, the founder of Nagano Electric Railway. He used the name for the flatlands and gently rolling terrain around the foot of Mount Shiga, including the areas around Lake Onuma, Maruike Pond, Hasuike Pond, Biwako Pond, and Kidoike Pond, as ski resorts and other facilities began to be developed.
Over time, the area associated with Shiga Kogen expanded toward Mount Yokote and the Ichinose district. Today, the name refers to a vast mountain resort region encompassing numerous peaks, lakes and ponds, ski areas, hot spring resorts, forests, and wetlands.
A Vast Protected Natural Environment
The Shiga Kogen Area Designated by Japan’s Ministry of the Environment
The area designated as the Shiga Kogen Region by Japan’s Ministry of the Environment covers approximately 24,986 hectares. Its broad boundaries extend from the Shiga-Kusatsu Road in the west to Kijimadaira Village, Nozawaonsen Village, and Sakae Village in the north, the Nakatsugawa River and Uonogawa River area in the east, and the border with Gunma Prefecture in the south.
Within this region, approximately 2,547.5 hectares are designated as a “Group Facilities District,” including areas with accommodation facilities and ski resorts.
A UNESCO Biosphere Reserve
Shiga Kogen is also recognized by UNESCO as a Biosphere Reserve, reflecting the importance of its ecosystems and the relationship between nature conservation and human activity.
The central area, including Mount Shiga and Lake Onuma, covers approximately 691 hectares and is designated as a core area. A surrounding area of approximately 17,569 hectares serves as a buffer zone. Including the transition area, the entire biosphere reserve extends across approximately 30,281 hectares.
This extensive protected landscape provides an important setting where conservation of mountain ecosystems can coexist with sustainable tourism and local livelihoods.
Climate: Cool Summers and a Snowy Winter Wonderland
Shiga Kogen has a humid continental climate and its high elevation gives it a considerably cooler climate than the lowlands of Nagano. Even in summer, temperatures above 30°C are relatively uncommon, and tropical nights are rare.
This refreshing climate has made Shiga Kogen a popular summer retreat for visitors seeking relief from the heat. The highlands offer comfortable conditions for hiking, sightseeing, and exploring the forests and wetlands.
Winter arrives early. The first snowfall is typically observed around the middle to latter part of October, and by November the region enters its main snow season. At Shibu Pass, which rises above 2,100 meters, annual snowfall can exceed four meters in some years, creating excellent conditions for winter sports.
Mountains and Geology Shaped by Volcanoes and Snow
Shiga Kogen is centered around Mount Shiga, rising 2,035.7 meters, and surrounded by a diverse collection of mountains including Mount Hachiyama, Mount Kasagatake, Mount Higashidate, and Mount Yokote.
To the northeast lies Mount Iwasuge and its highest summit, Ura-Iwasugeyama. To the north, ridgelines continue toward Mount Yakebitai, Mount Kenashiyama, and Mount Torikabuto. The result is a dramatic mountain landscape with an extraordinary variety of terrain.
Landscapes Created by Volcanic Activity
Past volcanic activity around Mount Shiga played an important role in shaping the surrounding landscape. Volcanic activity filled and altered valleys, contributing to the formation of striking natural features such as Makuiwa, Jummantaki Falls, and Naruhodaki Falls.
Volcanic landforms also created basins where ponds and wetlands could develop. These water-rich environments are now among the most valuable natural habitats in Shiga Kogen.
Landforms Shaped by Snow
Heavy snowfall has also left a powerful mark on the landscape. The eastern slopes of Mount Iwasuge contain cirque landforms, while the steep slopes of Mount Torikabuto feature terrain known as avalanche chutes, formed through repeated snow avalanches.
These geological and snow-shaped features reveal the powerful natural forces that have shaped the mountains over long periods of time.
The Geological Foundations of Shiga Kogen
The geological foundation of the region consists mainly of Miocene Green Tuff, which formed during the Tertiary period. These older rocks are overlain by volcanic rocks of the Takai volcanic group and later volcanic deposits from the Pleistocene.
Because of this long history of volcanic activity, visitors can encounter distinctive geological features including lava flows and columnar joints. The landscape of Shiga Kogen therefore offers not only beautiful scenery but also a fascinating record of volcanic processes.
Lakes, Ponds, and Waterfalls Created by Volcanoes
Approximately 200,000 years ago, volcanic activity blocked the course of rivers and created a dammed lake known as Lake Shiga. Subsequent volcanic and geological processes transformed parts of the area into wetlands, eventually producing the many ponds, marshes, and lakes scattered throughout today’s highlands.
The abundant water resources of Shiga Kogen have long been important to surrounding communities. Water from the mountains is used not only for the natural environment but also for agriculture and hydroelectric power generation.
Lake Onuma
Lake Onuma is one of the most famous natural features of Shiga Kogen. Its striking emerald-blue water contrasts beautifully with the surrounding forests and mountains, creating one of the region’s most memorable landscapes.
Shijuhachi-ike Wetland
Shijuhachi-ike Wetland is a beautiful highland wetland known for its alpine plants and birdlife. The area provides opportunities to observe seasonal flowers and wildlife while walking through the mountain landscape.
Jummantaki and Naruhodaki Waterfalls
Jummantaki Falls and Naruhodaki Falls demonstrate the interaction between volcanic terrain and flowing water. The combination of rugged rock formations, waterfalls, and surrounding forests creates dramatic scenery that changes with the seasons.
Four Seasons of Adventure in Shiga Kogen
Shiga Kogen is a true four-season mountain resort. The activities and scenery change dramatically throughout the year, allowing visitors to experience a different side of the highlands in every season.
Winter: One of Japan’s Great Ski Destinations
During winter, numerous ski areas are spread across the high-elevation parts of Shiga Kogen, including Mount Yokote, Kumano-yu, Ichinose, and Kogen-ga-hara.
The region’s high elevation and abundant snowfall provide excellent conditions for skiing and snowboarding. The area is particularly known for its light, dry powder snow, attracting winter sports enthusiasts from throughout Japan and overseas.
Spring to Autumn: Hiking and Alpine Flowers
When the snow melts, Shiga Kogen becomes a destination for hiking and mountain trekking. Trails lead toward peaks such as Mount Shiga and Mount Iwasuge, while the wetlands provide a chance to experience the delicate natural environment of the highlands.
At Shijuhachi-ike Wetland, seasonal alpine plants such as cottongrass and Nikko kisuge daylilies bloom beautifully. The changing colors and vegetation provide a completely different experience from the snow-covered landscape of winter.
A Place for Nature Observation and Environmental Education
The rich ecosystems of Shiga Kogen have also made the region an important field for nature education and environmental observation.
Nature centers in the area provide exhibitions introducing local plants and animals, as well as guided nature walks. These activities offer visitors an opportunity to learn about the mountain ecosystem while exploring the forests, wetlands, lakes, and alpine environments.
Experience the Changing Seasons of Shiga Kogen
Shiga Kogen is a remarkable natural landscape shaped by volcanoes, snow, forests, wetlands, and abundant water. Its appeal extends far beyond its famous ski resorts. Hiking, mountain scenery, alpine flowers, lakes, waterfalls, hot springs, wildlife observation, and winter sports can all be enjoyed within this vast highland environment.
In summer, the cool mountain air provides a refreshing escape from the heat. Autumn brings vivid foliage to the forests, while winter covers the highlands in deep snow. In spring, melting snow reveals wetlands and alpine plants as the landscape gradually awakens.
With its extraordinary natural diversity and dramatic seasonal changes, Shiga Kogen offers travelers the opportunity to experience a different face of the Japanese mountains throughout the year. Whether visiting for skiing, hiking, nature observation, or simply to enjoy the scenery, this vast highland resort provides an unforgettable encounter with the wild beauty of northern Nagano.