Ishimi Milestone

Ijimi Ichirizuka: A Pair of Edo-Period Road Markers on the San'in Highway

Two low, grassy mounds sit facing each other across a narrow lane in the Ijimi district of Shinji, near the southern shore of Lake Shinji in Matsue. They look modest, almost easy to walk past. Yet they are among the rarest survivors of a feature that once lined every major road in Japan: the ichirizuka, or one-ri marker. The Matsue Domain raised this pair in 1607 along the San'in-dō, the coastal highway that ran the length of the Sea of Japan side of the country. The mounds were designated a National Historic Site in 1937, and they remain one of only three confirmed ichirizuka anywhere in Shimane Prefecture.

Measuring the Road in Ri

An ichirizuka was a distance marker. In 1604 the Tokugawa shogunate ordered mounds placed at intervals of one ri, about 3.9 kilometers, along the main highways, counting outward from the Nihonbashi bridge in Edo. They were built in pairs, one on each side of the road, and usually planted with a pine or a hackberry. The tree gave travelers shade to rest in, and its roots held the packed earth together.

The markers did practical work. A traveler could read off how far the journey had run, and porters used the count to set fares for carrying people by palanquin or goods by packhorse. The system spread quickly, and within about a decade markers stood along the country's principal routes.

The Matsue mounds went up in 1607, three years after the national order, on the stretch of the San'in-dō that the domain itself built and maintained west of Matsue Castle. Counting from the castle, this is the fifth marker to the west. Counting from the old boundary between Izumo and Hōki provinces, it is the thirteenth.

Why So Few Remain

The Meiji government ordered the ichirizuka abolished in 1876. Most were leveled soon after, cleared for farmland, road widening, or the spread of towns. Of the many thousands once built nationwide, only seventeen survive today with national protection.

Shimane has just three confirmed examples: the Ijimi mounds here, the Yasugi Ichirizuka to the east, and the Shussai-Iwano Ichirizuka in Izumo to the west. The Ijimi pair earned its designation in 1937 because both halves had survived together, still set across the road from one another. The gap between them is about 5.5 meters, and that measurement is itself a piece of evidence. It records the width of the San'in-dō as the road ran through here in the Edo period.

Reading the Mounds

Each mound is a rounded heap of earth roughly five meters across. The northern one stands a little taller than its southern partner. The 1937 survey recorded both as somewhat higher than they are now; the centuries have settled and worn them down by perhaps half a meter.

When the site was surveyed for designation, both mounds still carried the pines planted on them generations before. The southern tree was substantial, its trunk close to four meters around. Those pines have since died, and the bare earthworks are all that is left. A visitor today reads the marker through its shape on the ground rather than through a crown of branches overhead.

Stand in the lane between the two mounds and you occupy the same five-and-a-half-meter corridor that once carried domain officials, merchants, and pilgrims along the coast. The road is quiet now. That quiet is part of what makes the place worth the detour: it is a working piece of seventeenth-century infrastructure left more or less where it was put.

The Setting Around Lake Shinji

The marker lies a short way south of Lake Shinji, the brackish lagoon known for its evening light and for the shijimi clams gathered from its shallows. The lakeside town of Shinji served as a post station on this same road in earlier centuries, so the area's links to travel and traffic run deep.

Matsue, a little over ten kilometers to the east, is the obvious base for a visit. Its castle keep, built of wood in the early 1600s, is a National Treasure and one of only twelve original keeps left standing in Japan. The hot-spring town of Tamatsukuri lies between the city and the lake's southern shore. Westward, the road continues toward Izumo and its great shrine.

The site sits close to the JR San'in Main Line. Reaching it by car is the simplest approach, since the mounds stand on a back lane rather than a through road, and there is little in the way of formal visitor facilities at the spot itself.