Iroha Slope

Iroha Slope, a steep sightseeing road with 48 characteristic curves, connects downtown Nikko with Lake Chuzenji and Oku-Nikko.

The road consists of two slopes, the first Iroha slope for downhill and the second Iroha slope for uphill, and the total number of sharp curves on the two slopes is as many as 48.

Each curve is marked with a “I”, “RO”, “HA”... sign, allowing visitors to enjoy the drive while having fun. The road continues steeply uphill, with an elevation gain of 440 meters.

From the Akechidaira Observatory on the way to the second Iroha slope (uphill only), you can enjoy a wonderful view and a view of the first Iroha slope.

In autumn, it is known as one of the most beautiful spots in Nikko for autumn foliage, and is a superb driving course, so popular that it is jammed with traffic.

We recommend that you allow plenty of time for your visit during the fall foliage season. (It is not unusual for a trip that normally takes about 20 minutes to take two to three hours when there is traffic congestion.)

This mountain road was selected as one of the 100 best roads in Japan, and was once used by worshippers to Nantai-san and Chuzen-ji Temple.

Iroha-zaka (Irohazaka) is a slope on National Route 120 from Umagae to Chuzenji Lake in Nikko City, Tochigi Prefecture.

The name Iroha-zaka comes from the 48 hairpin curves on the early Iroha-zaka. The current Iroha slope has been improved, with the first Iroha slope on the north side being for downhill only and the second Iroha slope on the south side for uphill only. These two slopes have a total of 48 curves, each with a letter board. The two slopes meet at Umagae and Chuzenji Lakeside.

The second Iroha slope is a one-way uphill road from Umamari to Chuzenji Lake, with 20 curves from “I” to “N”. On the other hand, the first Iroha slope is a one-way descent from Lake Chuzenji to Umabore, with 28 curves from “Na” to “N”. There are two rest areas and parking lots along the Second Irohazaka, and at Akechidaira, the ropeway station house offers a panoramic view of Kegon Falls and Lake Chuzenji.

Iroha-zaka used to be a toll road, but is now open to the public free of charge and has been selected as one of the 100 best roads in Japan as “48 Curved Roads. The steep gradient and curves of the road make for beautiful scenery of fresh greenery in spring and autumn leaves in fall. As a result, it can be crowded during the spring and fall tourist seasons.

Wild Japanese macaques live along the route, but there are problems caused by tourists who feed them. There have been reports of souvenirs being stolen, and Nikko City has enacted the nation’s first “no feeding” ordinance.

Iroha-zaka (いろは坂) is a mountain road that originated from a place known as the sacred site of Mt. Nantai, which was opened in 782 during the Nara period (710-784). The early Iroha-zaka has 48 hairpin curves, and its name derives from its features.

Until the early Meiji era (1868-1912), Nantai-san was closed to women and cattle and horses. As a remnant of this, the place name “Umagae” and the “Women’s Hall” in the middle of the first Iroha slope still remain. In the Taisho era (1912-1926), traffic increased and a road to Lake Chuzenji was constructed. However, the road at that time was a gravel road and narrow, making it difficult to pass each other.

In 1952, Tochigi Prefecture began full-scale road improvement as a trunk road connecting Nikko and Oku-Nikko. The Iroha-zaka section was also improved and opened to traffic in 1954 as the second toll road in Japan. Thanks to this road, it is now possible to reach the shore of Lake Chuzenji in about 20 minutes from Umagae.

With the opening of Iroha-zaka, the number of tourists to Oku-Nikko increased, but traffic congestion also became chronic. In 1984, the road was opened to the public free of charge.

The Daini-Iroha slope is for mountain climbing only, and the section from Akechidaira to the Chuzenji lakeside is a one-way road. It used to be a two-way road, causing traffic congestion, but in 2019, it was converted to two lanes in each direction and is now completely dedicated to mountain climbing.

Iroha-zaka is a historical road and an essential part of sightseeing to Oku-Nikko. Its beautiful scenery and rich history offer a lot of attractions for many people.

■Forest of the Fall Foliage in Oku-Nikko (approximate time)
　Yunoko and Yudaki: Early to mid-October
　Kotoku Ranch: Mid-October (autumn leaves), late October (yellow leaves (larch))
　Senjogahara and Odashirobaru: late September to early October (grassy autumn leaves), early to mid-October (autumn leaves), late October (yellow leaves (larch))
　Ryuzu Falls: early to mid-October
　Lake Chuzenji：Mid to late October
　Kegon Falls：Mid to late October
　Iroha-zaka slope：Mid to late October
*The best time to see the flowers is in a typical year. They may change depending on the weather of the year.