Oshu Highway

Oshu Kaido: Walking the Edo Period's Great Northern Highway

Hidden in the wooded hills of northern Iwate Prefecture lies a remarkable surviving fragment of feudal Japan: a quiet earthen road, lined in places with mossy mounds and the ghosts of cedar avenues, that once carried samurai retinues, palanquins, post horses, and merchant caravans on their long journey between Edo and the far north. This is the Oshu Kaido (奥州街道), one of the five great highways established by the Tokugawa shogunate in the early 17th century. While most of its 800-kilometer length has long since been buried beneath modern asphalt, in the towns of Ichinohe and Iwate-machi some of the most evocative unpaved sections of the original road still wind through the mountains exactly as travelers knew them three centuries ago.

In 2010, the national government designated these surviving stretches as a National Historic Site — the first time in modern Japanese history that the route of one of the Five Highways itself, rather than a single bridge or post-town, received that level of protection. For visitors who want to step off the bullet train and into the Edo period, this corner of northern Iwate offers something genuinely rare: not a reconstruction, but the real road.

What Was the Oshu Kaido?

When Tokugawa Ieyasu consolidated power in the early 1600s, his shogunate organized five major arterial highways radiating outward from Nihonbashi in Edo (modern Tokyo). These Gokaido — the Tokaido, the Nakasendo, the Koshu Kaido, the Nikko Kaido, and the Oshu Kaido — became the circulatory system of early modern Japan. They moved the alternate-attendance processions of feudal lords, the official couriers of the shogunate, and the rice, salt, lacquer, and silk that fed the new urban economy.

In its strict legal sense, the Oshu Kaido was relatively short, running from Edo north to Shirakawa in present-day Fukushima. But in everyday use, the name extended far beyond that. Travelers, mapmakers, and the post-station system all spoke of a continuous "Oshu Kaido" that pushed on through Sendai, Morioka, Hachinohe, and finally to Sotogahama on the Tsugaru Peninsula at the very tip of Honshu. Along this longer route lay 114 post stations where horses were exchanged, weary travelers slept, and goods changed hands.

By the late Edo period, the road had taken on military significance as well. Russian ships were appearing in the waters off Ezo (Hokkaido), and the shogunate increasingly viewed the northern highway as a strategic supply line for defending the realm's northern frontier. After the Meiji Restoration, the young emperor himself traveled the road in 1876 and again in 1881 during his great tours of the Tohoku region, prompting the highway to be widened to roughly 3.6 meters to accommodate his horse-drawn carriages.

Why Northern Iwate? A Happy Accident of History

Most of the old Oshu Kaido has vanished. As Japan modernized after 1868, new national roads were built — wider, straighter, easier on wheeled vehicles — and these typically followed the old highway closely or sat directly on top of it. Today, much of Route 4 traces the original path. But around Ichinohe and Iwate-machi, something different happened.

When work began in 1884 on a modern national road through the area, planners chose an entirely different alignment, leaving most of the Edo-period road behind in the hills. With its commercial purpose gone, the old road slipped quietly out of use. Farmers used the easier sections; the harder ones reverted to forest path. And precisely because nothing important happened to it, the road survived. The wagon-rutted earth, the stone retaining walls, the avenues of trees, and four magnificent ichirizuka — the paired earthen mounds that marked each ri (about 3.9 km) of distance — all remained intact.

Today, the protected area covers seven unpaved sections totaling 8.86 kilometers, plus four sets of ichirizuka. From the Mido-Mabamatsu Ichirizuka at Ichinohe's southern boundary to the Namiuchi-toge Ichirizuka at its northern edge, the full route through the town stretches about 24 kilometers — a walkable, immersive corridor through Edo-period Japan.

Why It Earned National Historic Site Status

The Agency for Cultural Affairs evaluated this stretch of the Oshu Kaido using several criteria, and on every count it stood out. The unpaved roadbed retains the original Edo-period width, drainage, and gentle gradient. The four ichirizuka — at Namiuchi-toge, Kawasoko, Kyu-Nakayama, and Mido-Mabamatsu — survive in pairs, which is increasingly uncommon (most surviving ichirizuka in Japan have lost one of their two mounds to road widening or development). The setting, too, remains remarkably unchanged: forested ridgelines, valley bottoms, and small mountain hamlets that would still be recognizable to a traveler from 1850.

Crucially, this designation marked the first time that one of the Five Highways was protected as a road — not as a single famous landmark along it, but as the route itself. That distinction reflects the Agency's recognition that the Oshu Kaido through northern Iwate is, in essence, an open-air museum of Edo-period transportation.

Highlights Along the Way

Walking Routes for Visitors

The Ichinohe Tourism Association has mapped four loop walking courses, each starting from a station on the IGR Iwate Galaxy Railway, which conveniently parallels the modern route. Each course mixes Oshu Kaido sections with other local attractions, and most can be completed in a single day.

• Town and Pass Loop (Ichinohe Station, ~12 km, ~6 hours): Includes Namiuchi-toge Ichirizuka, the Namiuchi cross-bedding cliffs, the great ginkgo of Jisso-ji Temple, and the Ichinohe Castle ruins.
• Valley Loop (Kotsuya Station, ~13 km, ~7 hours): Visits the Fujishima wisteria, the Kawasoko Ichirizuka, and the historic former Hoki-date House.
• Difficult-Pass Highland Loop (Kotsunagi Station, ~10 km, ~6 hours): Explores the Kotsunagi guard-post site, the Kotsunagi Ichirizuka, and the steep Yono-zaka slope.
• Ridge Trail Loop (Okunakayama Kogen Station, ~13–15 km, ~7 hours): Takes in the Kyu-Nakayama Ichirizuka, the Aomen-Kongo stone statue, an Imperial rest spot, and the Mido-Mabamatsu Ichirizuka.

Local guides can be arranged in advance through Ichinohe Town Hall's Cultural Properties Section.

Around the Area

The Oshu Kaido walks pair well with several nearby cultural sites. The Goshono Jomon Site Museum, in central Ichinohe, interprets the UNESCO World Heritage-listed Goshono archaeological site — a remarkable Jomon-period village dating back 4,000 to 5,000 years. Just south, in Iwate-machi, the gentle landscape of the Iwate Highlands invites cycling and birdwatching. To the north, Ninohe City offers Tenshochi shrine and the lacquer-making village of Joboji, famous for producing the urushi sap used to restore Japan's most important wooden temples.

For meals, Ichinohe is known for its Nanbu cuisine, including hittsumi (a hand-torn wheat dumpling soup) and locally raised Tankaku beef. Onsen lovers can soak at Okunakayama Kogen Onsen near the southernmost station on the loop courses.