Hasaike Tomb

Hasaike Kofun: An Untouched Window into 1,400-Year-Old Burial Rites

Hasaike Kofun, nestled atop a 121-meter hill in the northeastern part of Matsuyama City in Ehime Prefecture, is a remarkable late Kofun-period burial mound dating from the mid-6th to early 7th century. Discovered entirely by chance in 1992, this elongated oval tumulus contains five separate burial chambers, two of which—Stone Chambers No. 1 and No. 2—were found completely undisturbed by ancient grave robbers, an extraordinary rarity in Japan.

Most horizontal stone chambers in Japan have been disturbed at some point over the centuries because their entrance design makes access relatively easy. Hasaike Kofun, however, escaped the attention of robbers entirely. As a result, its sealed chambers preserved wooden coffins, ceramic offerings, and the physical traces of ancient funerary ceremonies in their original positions. The site functions almost like a time capsule, allowing modern visitors and researchers to glimpse how the people of western Shikoku honored their dead some 1,400 years ago.

The Story of Its Discovery

The existence of Hasaike Kofun came to light in June 1992, when the landowner attempted to clear the property using heavy machinery. The bucket of an excavator struck one of the capstones of what would later be identified as Stone Chamber No. 1, exposing the hidden burial chamber beneath. Fortunately, the interior suffered no significant damage, and through the gap a glimpse of Sue ware ceramic vessels and the remains of wooden coffin material confirmed that something extraordinary lay below the surface.

Recognizing the site's importance, Matsuyama City quickly purchased the land and launched a full academic investigation in 1993. Five separate excavation campaigns were carried out between 1993 and 2008, gradually revealing the mound's structure, its five burial chambers, and the complex sequence of construction phases. After nearly two decades of careful study, Hasaike Kofun was designated a National Historic Site on February 7, 2011, becoming the fourth such designation in Matsuyama City and a milestone for the region's cultural heritage administration.

Why This Tumulus Earned National Recognition

Hasaike Kofun received its national designation primarily because it offers an unparalleled opportunity to reconstruct late Kofun-period funerary practices in concrete, physical detail. The presence of multiple undisturbed horizontal stone chambers within a single mound is virtually unprecedented in Japan, and the chambers preserve the full sequence of activities from initial interment through repeated additional burials and ritual offerings.

One of the most striking discoveries involved the human remains found in Stone Chamber No. 1. Archaeologists identified large quantities of fly pupae casings adhering to the bones, and because the species in question prefers sunlit environments, this evidence demonstrated that the deceased had been laid out in a place exposed to daylight for roughly seven to ten days before being placed inside the chamber. This physical confirmation of the ancient practice known as "mogari"—a form of temporary above-ground entombment described in early Japanese texts—was a major scholarly breakthrough. In addition, an installation containing the lower jawbone of a horse was discovered, suggesting that animal sacrifice formed part of the mound's construction rituals. Together, these findings transformed scholarly understanding of how death was approached in ancient western Japan.

Highlights of a Visit

Hasaike Kofun Park has been thoughtfully developed to balance preservation with public access, allowing visitors to experience this remarkable site without disturbing its archaeological integrity.

Nearby Attractions

The eastern part of Matsuyama City offers a wealth of cultural and historical sites that complement a visit to Hasaike Kofun. Travelers exploring the area may wish to combine the tumulus with the following destinations.

• Matsuyama City Archaeological Museum — Houses many of the artifacts excavated from Hasaike Kofun and other archaeological sites across the city.
• Matsuyama Castle — One of only twelve original Edo-period castle keeps remaining in Japan, perched dramatically on Mount Katsuyama in the city center and designated an Important Cultural Property.
• Dogo Onsen Honkan — One of Japan's oldest hot spring bathhouses, with a history stretching back approximately three millennia, designated as a nationally Important Cultural Property.
• Yuzuki Castle Ruins — A National Historic Site that served as the stronghold of the Kono clan, governors of medieval Iyo Province, located within the same city as Hasaike Kofun.