One of Eastern Japan’s Earliest Kofun
Kōbōyama Kofun is a zenpō-kōhō-fun, a distinctive type of burial mound with a square rear section and a smaller square front section connected at the center. This form differs from the more familiar keyhole-shaped kofun found elsewhere in Japan.
Its construction is estimated to date from the late 3rd to mid-4th century, placing it among the earliest kofun in eastern Japan. Its age and distinctive design make it particularly valuable for understanding how the culture of large burial mounds spread across the Japanese archipelago.
The Scale and Structure of the Burial Mound
The mound has a total length of approximately 66 meters. The rear section measures about 47 meters wide and 41 meters long, with a height of approximately 7.15 meters.
The front section is approximately 22 meters wide and 25 meters long, rising about 3.5 meters above the surrounding ground.
Only limited evidence of fukiishi, or stones covering the outer surface of the mound, has been identified. No surrounding moat or haniwa clay figures have been found, providing an interesting contrast with some of the large kofun constructed in later periods.
The Burial Chamber
The main burial facility was placed in the center of the rear section. It takes the form of a rekikaku, a stone-lined burial chamber resembling a pit-style stone chamber.
The chamber was constructed by stacking river stones and measures approximately 5 meters long, 1.3 meters wide, and 93 centimeters deep. Black earth was placed inside, and archaeologists believe that the deceased was originally buried in a wooden coffin.
Remarkable Burial Goods
A large number of valuable objects were discovered inside the burial chamber. Among them was a half-triangular-rimmed mirror decorated with four animals and bearing an inscription referring to “Jōhō-saku”.
Other finds included bronze arrowheads, an iron sword, an iron axe, magatama curved beads, 738 small glass beads, and pottery including S-shaped jars.
These burial goods indicate that the person buried here held considerable status. They also provide evidence of connections with regions far beyond the Matsumoto Basin.
Connections with the Tokai and Kinai Regions
Some of the pottery discovered at the site is strongly associated with the Motoyashiki-style pottery of the Nōbi Plain. This is particularly significant because the Nōbi region lies in what is now central Japan, suggesting that the people connected with Kōbōyama Kofun maintained links with the Tokai region and the Kinai region around present-day Nara and Osaka.
The combination of imported or regionally distinctive objects, mirrors, beads, and pottery suggests that the individual buried at Kōbōyama was not simply a local figure but may have been a powerful regional leader involved in wider networks of exchange.
Today, the excavated objects are preserved and displayed at the Matsumoto City Archaeological Museum, where visitors can learn more about the discoveries and the society that created the burial mound.
The Rise of Regional Rulers
The origin of the zenpō-kōhō-fun form is thought to be connected with square moated tombs found in the Tokai region during the late Yayoi period.
Kōbōyama Kofun appears to reflect this developing tradition at a time when political power was becoming increasingly concentrated in the hands of regional leaders. The objects buried with the deceased suggest connections with the Nōbi Plain and the Kinai region, indicating that Matsumoto was already part of broader cultural networks more than 1,600 years ago.
This was a period of major political change in Japan, associated with the emergence of powerful regional groups and the historical world surrounding figures and polities such as Yamatai and Kunu.
A Strategic Hill with a Magnificent View
The location of Kōbōyama Kofun is as impressive as the archaeological remains themselves. The mound stands on a hill overlooking the Matsumoto Basin, with expansive views toward the surrounding mountains and agricultural landscape.
From the top of the mound, visitors can look across broad areas of rice fields, with approximately 70 hectares to the north and 40 hectares to the west visible from the elevated site.
The commanding location may have carried symbolic significance. Constructing an important burial mound on a prominent hill overlooking the territory would have created a powerful visual presence, reinforcing the status of the person buried there as a regional leader.
The site can therefore be understood as a kind of “kunimi hill”, a place from which a ruler could symbolically survey the land under their influence.
A Famous Cherry-Blossom Destination
In spring, Kōbōyama becomes one of Matsumoto’s best-known cherry-blossom viewing spots. Approximately 2,000 cherry trees, including Somei Yoshino and yaezakura varieties, grow around the hill.
When the trees bloom, the paths and slopes are surrounded by a spectacular corridor of flowers. The combination of pink blossoms, the historic burial mound, Matsumoto’s urban landscape, and the distant Northern Alps creates an especially memorable scene.
The site is popular with both local residents and visitors during the cherry-blossom season. It is also a favorite location for photography, particularly when the flowers frame the mountains and city below.
The view from Kōbōyama has become widely recognized as an iconic image of Matsumoto and is frequently used when introducing the city and its surrounding landscape.
A National Historic Site
Kōbōyama Kofun was designated a National Historic Site in 1976, recognizing its outstanding archaeological importance.
The artifacts excavated from the burial chamber were later designated a Nagano Prefectural Treasure in 1993. Together, these designations reflect the importance of both the burial mound itself and the archaeological evidence preserved within it.
The Matsumoto City Archaeological Museum also plays an important educational role by presenting excavation results and artifacts, allowing visitors to understand the history of the Kofun period through actual archaeological discoveries.
Visiting Kōbōyama Kofun
Kōbōyama Kofun can be reached in approximately 30 minutes on foot from JR Minami-Matsumoto Station.
Another option is to take an Alpico Transportation bus from Matsumoto Bus Terminal on the Namiyanagi Danchi Line. Get off at Kōbōyama Iriguchi, followed by a walk of approximately 10 minutes.
By car, the site is approximately 20 minutes from either Matsumoto Interchange or Shiojiri-kita Interchange.
Combine Ancient History with Matsumoto’s Castle Town
Kōbōyama Kofun can easily be combined with sightseeing in central Matsumoto. After exploring this ancient archaeological site, visitors can continue to Matsumoto Castle, Nakamachi, and Nawate Street to experience completely different chapters of the city’s history.
The contrast is particularly fascinating: at Kōbōyama, visitors encounter evidence of a society more than 1,600 years old, while in the city center, preserved streets and buildings reveal Matsumoto’s development as an Edo-period castle town.
Ancient History and Alpine Scenery in One Place
Kōbōyama Kofun is a rare destination where archaeology and scenery come together. The ancient burial mound preserves evidence of the emergence of powerful regional leaders and their connections with distant parts of Japan, while its hilltop setting provides sweeping views across the Matsumoto Basin and toward the Northern Alps.
In spring, the approximately 2,000 cherry trees add another layer of beauty, turning the historic landscape into a spectacular place for a seasonal walk.
For travelers interested in ancient Japan, archaeology, traditional landscapes, or simply beautiful views of Matsumoto, Kōbōyama Kofun offers a unique opportunity to experience the city’s history from a perspective that reaches back to the very beginning of the Kofun period.