Nikko's Senjo-ga-hara Marshlands

Battlefield Folklore

By Tomoko Kamishima    - 3 min read

Huge numbers of snakes and centipedes became entangled and bit each other in the ancient field of inner Nikko. The fight seemed to last forever and the field looked like a wasteland at the end of the earth. This is the story of how Senjo-ga-hara was formed, and why it has this name: Senjo means “place of battle” and hara means “field”

The god of Mt. Nantai (Tochigi prefecture) and Mt. Akagi (Gunma prefecture) had been fighting a territorial dispute over Chuzen-ji Lake about 20,000 years ago. They insisted the lake was their own. Mt. Nantai incarnated into a huge serpent and had a large force of snakes under his control. On the other hand Mt. Akagi incarnated into a giant centipede and had a vast army of centipedes with him. The war was not going in Mt. Nantai’s favor and was almost lost. Then Mt. Nantai asked his grandson, Sarumaru to help him. Sarumaru was an expert archer. As soon as Sarumaru entered the battle, he found the giant centipede that controlled the fight, and aimed an arrow at its left eye. The arrow hit the giant centipede and it started bleeding from its eye. The red blood stained the marsh near the field with a deep red color (this place is named “akanuma” or “red marsh”). All the centipedes ran away and the battle was over.

Outline of Senjo-ga-hara marshland

The marshland is a high moor (1390-1400 m above sea level) and you can often observe bog moss covering trees and wood. The whole area has been drying up gradually, but still you can see different kinds of vegetation in different sections. Basically, the north part has scattered low trees with reeds, the west part is still wetland, and the south part features some highland flowers such as cotton grass and azaleas.

The hiking course

There are a few walking trails through the marshland that connect the Akanuma bus stop and the Yudaki Iriguchi bus stop. These (roughly) two-hour trails are called Senjo-ga-hara Shizen Kenkyu-ro. To protect the nature of the marshes here, a wooden walkway has been built along the Yukawa River. The course is mainly flat and easy to walk, but is full of the wonders of nature and has a beautiful mountain view. You will see many other hikers passing by. Please exchange greetings and enjoy conversations with them.


The end of the course is Yudaki Falls, which gradually drops 50-75 meters from Yuno-ko Lake to Yukawa River. Yukawa River becomes Ryuzu-no-taki Falls and then pours into Chuzen-ji Lake. You can see the falls from the bottom, standing on a well-placed observation deck. It’s both beautiful and exciting at the same time!

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Tomoko Kamishima

Tomoko Kamishima @tomoko.kamishima

Japan is a small island nation, but we have a huge number of surprising things to discover here. Many of these delights can be found when you step off the main street onto small side paths. I really enjoy studying about and researching various aspects of traditional Japanese culture, and then sharing this information with visitors to Japan. I hope you will enjoy it, too! ARTICLE INDEX & PHOTOS:  An index of most of my Japan Travel articles can be found at the entry page of my blog, and my photos are shown here.  日本はとても小さな国ですが、大通りから一本小道に入ればたくさんの発見があります。日本人が積み重ねてきた歴史を学びながら、古い建物や庭を訪ね、物語の舞台となった景色を眺めて、皆様といっしょに日本文化の奥深さを探求していきたいと思います。

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