Two Surviving Burial Mounds
The Mizuwakasu Shrine Tumulus Cluster originally formed part of a larger archaeological landscape, while Tumulus No. 1 and Tumulus No. 2 are the two surviving mounds visible today. Each offers different clues about the burial customs and stone-working techniques of ancient Oki.
Tumulus No. 1 and Its Remarkable Stone Chamber
Tumulus No. 1 lies to the east of the shrine’s main sanctuary. The original burial mound has disappeared, leaving its exceptionally large horizontal stone chamber exposed. At approximately 11 meters long, it is regarded as one of the largest stone burial chambers in the Oki Islands.
The chamber consists of an entrance passage, or sendō, and a burial chamber, or genshitsu. Two coffin-shaped sarcophagi carved from tuff stone have been identified inside the chamber.
The layout may have included multiple chambers, with a separate front chamber positioned before the main burial chamber. This unusual arrangement may reflect complex burial rituals and the high social status of the individuals buried here.
The tomb has not been completely excavated. Soil has accumulated inside the stone chamber, and future archaeological research may reveal additional information about the people buried here and the circumstances surrounding their deaths.
Tumulus No. 2
Tumulus No. 2 is a circular burial mound located behind the shrine’s main sanctuary. It measures approximately 20 meters in diameter and 2.5 meters high, and its overall form remains relatively well preserved.
Part of the mound was altered when the shrine’s main sanctuary was constructed, but enough of its original shape remains to appreciate its scale. Its presence immediately behind the shrine creates a striking landscape in which an ancient burial site and a later sacred precinct coexist.
Valuable Artifacts from Tumulus No. 1
A variety of artifacts associated with Tumulus No. 1 provide insight into the lives and status of people in late Kofun-period Oki. Finds include pottery, an iron sword, an iron agricultural tool, iron arrowheads, and glass beads.
These objects are now housed in the Tokyo National Museum. They provide evidence not only of local craftsmanship and burial customs but also of the wider cultural connections maintained by the people of Oki.
The glass beads are particularly interesting because such ornaments could signify status and social position. Their presence in the tomb suggests that the person buried there belonged to an influential social group.
History of the Site and Its Discovery
The tumuli are generally thought to have been constructed during the late 6th century, a period when burial mounds were being built throughout the Japanese archipelago. Their existence demonstrates that Oki, despite its island location in the Sea of Japan, had communities with sufficiently strong political and economic influence to construct substantial burial facilities.
The relationship between the ancient tombs and the present-day shrine is particularly intriguing. The current Mizuwakasu Shrine was relocated to its present site during the Edo period, and the tumuli are not considered to have been directly connected with the shrine when they were originally constructed.
Nevertheless, their survival within the later shrine precinct illustrates the remarkable accumulation of history in this landscape, where an ancient burial ground and a much later religious institution now stand side by side.
The tumulus cluster was discovered in 1920 during construction work to expand the shrine grounds. It was subsequently recorded in the Shimane Prefectural History in 1925. Several academic investigations have been carried out since the postwar period, although the entire site has never undergone a full-scale excavation.
Who Was Buried Here?
The identities of the people buried in the tumuli remain unknown. However, researchers have pointed to a possible connection with the nearby Inumachi Temple Ruins, also known as the Kōri Temple Ruins.
The temple is thought to have been associated with an influential local group, and some researchers suggest that members of this elite community may have been buried in the Mizuwakasu Shrine tumuli.
If so, the site provides an important glimpse into the people who may have shaped the political, religious, and cultural development of ancient Oki. The tombs can therefore be viewed not simply as burial places, but as traces of an influential community that once played a central role on the islands.
Mizuwakasu Shrine: A Historic Setting for the Tumuli
The tumulus cluster is located within the grounds of Mizuwakasu Shrine, one of the most important shrines in Oki. Recognized as the Ichinomiya of Oki Province, the shrine has been revered since ancient times and is closely connected with the history and traditions of the islands.
Distinctive Oki-zukuri Architecture
The shrine’s main sanctuary was constructed in 1795 and is designated an Important Cultural Property of Japan. Its thatched roof, chigi finials, and katsuogi roof ornaments are characteristic of the distinctive Oki-zukuri architectural style.
Oki-zukuri combines elements associated with several major Japanese shrine traditions, including the architectural styles of Ise Jingu, Izumo Taisha, and Kasuga Taisha. Seeing this distinctive building alongside the ancient tumuli makes the shrine grounds particularly rewarding for visitors interested in Japanese history and architecture.
Traditional Festivals and Local Culture
Every other year, on May 3, Mizuwakasu Shrine hosts the Sailei Furyū festival. Traditional events include the Yamabiki ritual and yabusame, or ceremonial horseback archery.
The festival offers an opportunity to experience Oki’s living cultural traditions and to see how the shrine continues to serve as an important gathering place for the local community.
Discovering Ancient Oki Through the Tumulus Cluster
The Mizuwakasu Shrine Tumulus Cluster offers a rare opportunity to explore the ancient history of the Oki Islands in an exceptionally atmospheric setting. The huge stone chamber of Tumulus No. 1, the well-preserved form of Tumulus No. 2, and the artifacts recovered from the site all provide clues about the people who lived here more than 1,400 years ago.
At the same time, the surrounding shrine grounds reveal another layer of Oki’s heritage through traditional architecture, religious traditions, and festivals that have continued into the present day.
From Saigo Port, the site can be reached in approximately 25 minutes by car, with bus services also available. Nearby attractions such as the Oki Folk Museum and Goka Soseikan can be combined with a visit to create a deeper exploration of the islands’ history and culture.
For travelers interested in archaeology and traditional Japan, walking among the ancient tombs before exploring Mizuwakasu Shrine provides a memorable way to experience the long and layered history of Oki.