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History and Origin of "Irohazaka"

"Irohazaka" refers to a section of the national highway connecting Nikko city center and Lake Chuzenji.
It consists of the "Second Irohazaka" for ascending traffic and the "First Irohazaka" for descending traffic, both of which are one-way roads.
The "First and Second Irohazaka" have 48 curves, and because each curve is named after one of the 48 characters of the "Iroha" alphabet, it is called "Irohazaka." Signs are posted at each curve, with the ascending Second Irohazaka featuring the 20 characters from "i" to "ne," and the descending First Irohazaka featuring the 28 characters from "na" to "n."

The history of "Irohazaka" dates back to the Nara period, rooted in mountain worship with Mount Nantai as the object of devotion.
As it was a sacred path for climbing to worship at Mount Nantai, women and horses/cattle were prohibited from entering until the early Meiji period. In the Showa era, a road was developed and paved to connect Mount Nantai with Nikko city center, which became the current Irohazaka.

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Highlights of the autumn leaves at Irohazaka

The best season for Irohazaka is the autumn foliage season.
The autumn leaves in Oku-Nikko typically begin around early October near "Ryuzu Falls (1,350m)" and descend toward Nikko city center over about two months.
The best time to enjoy the vibrant autumn leaves at "Irohazaka," which is located along the way, is usually from mid-October to early November.

The autumn foliage of Irohazaka, showing different faces due to the difference in elevation

"Irohazaka" has a significant elevation difference, with the foot of the mountain at Umagaeshi at an altitude of about 800m and Lake Chuzenji at about 1,260m, so the timing of the autumn leaves varies depending on the altitude.
The beautiful colors of the autumn leaves are created by the temperature difference between day and night and the temperature difference due to altitude, and the shades of the leaves also vary, so you can enjoy different expressions every time you visit during the autumn foliage season.

The view of the autumn foliage from Akechidaira is spectacular

Near the end of the "Second Irohazaka Slope," there is a rest area at Akechidaira, where a ropeway departs for the Akechidaira Observatory.
From the Akechidaira Observatory, you can enjoy a panoramic view of Lake Chuzenji, making it a truly spectacular spot for autumn foliage.
Since Akechidaira can only be accessed from the uphill "Second Irohazaka Slope," be careful not to miss the entrance after passing the "Ne" curve.
*The ropeway is closed for renovation work until August 31, 2027.

Types of autumn foliage that can be enjoyed on Irohazaka

At Irohazaka, you can mainly enjoy the autumn colors of maple, Japanese rowan, azalea, and katsura trees.

Maple

The fresh green of spring is beautiful, and these familiar trees, which turn red and yellow in autumn, are widely distributed throughout the "Irohazaka Slope."

Japanese rowan

The Japanese rowan, which bears small red berries, turns a "fiery, vibrant red" during the autumn foliage season, creating a vivid contrast against the blue autumn sky.

Azalea

It turns an orange-red color, creating a beautiful landscape with a gradient against the bright red Japanese rowan.

Katsura tree

During the autumn foliage season, it turns yellow.
Depending on the time, the mix of yellow and green leaves, combined with the colors of maples, Japanese rowan, and azaleas, creates a natural, exquisite beauty that delights the eyes.

We have introduced some representative types of trees that change color in autumn, but at "Irohazaka," many trees across various elevations are preparing to color the landscape with spectacular autumn foliage.

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Access by car and traffic information

You can usually reach "Irohazaka" by car in about 2.5 hours from the city center, and it is about a 15-minute drive from the Kiyotaki IC on the Nikko-Utsunomiya Road.
The uphill "Second Irohazaka Slope" is a 9.5km road that usually takes about 20 minutes to drive, but during the autumn foliage season, it can take 2 to 3 hours, so be sure to check traffic information frequently.

Traffic information for Irohazaka can be checked on the Nikko Traffic Congestion Site or the official Nikko Kamen X account.

How to avoid the Irohazaka Slope, where heavy traffic is expected even on weekdays

Even on weekdays, it gets crowded with autumn foliage tour buses and the like, so we recommend traveling early in the morning to avoid traffic jams.
Also, if it is a weekday, you should plan to start ascending the Irohazaka Slope by 7:00 AM and calculate your departure time accordingly.
To avoid getting caught in traffic on the way back as well, it is best to descend the Irohazaka Slope by 3:00 PM at the latest.

Be prepared for even worse traffic on weekends and holidays

According to traffic forecast information, traffic jams during weekends in the autumn foliage season are expected on the Irohazaka Slope from 7:00 AM to 8:00 AM for the ascent, and from 3:00 PM to 7:00 PM for the descent.
It is no exaggeration to say that once you are stuck in traffic, you will not be moving at all.
To avoid traffic, it is recommended to ascend the Irohazaka Slope by 6:00 AM and descend before 2:00 PM.
Also, if there are events in Nikko city, even more traffic is expected, so be sure to check for those as well and plan your travel carefully.

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Access by public transport

If you take a bus bound for Chuzenji Onsen or Yumoto Onsen from JR Nikko Station or Tobu Railway's Tobu-Nikko Station, you will normally arrive at Akechidaira in about 40 minutes.
The Irohazaka Slope is often congested during the autumn foliage season, so using public transportation is also recommended as a way to enjoy the autumn leaves with a relaxed state of mind.

The autumn foliage on the Irohazaka Slope, which has been selected as one of the "100 Best Roads in Japan," is a spectacular sight. Gather information, prepare,
and enjoy the wonderful scenery.