Hotoketsuka Kofun is a square burial mound located in Horyu-ji, Ikaruga Town, Ikoma District, Nara Prefecture. It is protected as a Prefectural Historic Site of Nara. The mound was built at the tip of a small ridge extending northward from Terayama, a low hill north of Horyu-ji Temple in the northwestern part of the Nara Basin.
The name “Hotoketsuka,” which can be translated as “Buddha Mound,” reflects the site’s later history. During the medieval period, the ancient burial mound was reused as a Buddhist hall, and numerous Buddhist statues and ritual implements were discovered there. These finds gave the site its distinctive name.
In fiscal year 1976, archaeological excavations were conducted by the Nara Prefecture Kashihara Archaeological Institute and the Ikaruga Town Board of Education, revealing important details about the mound’s construction and historical significance.
Hotoketsuka Kofun is square in shape, measuring approximately 23 meters on each side and standing more than 4 meters high. Soil used to construct the mound was taken from surrounding archaeological deposits. During excavation, researchers also discovered fragments of Jomon-period and Yayoi-period pottery, as well as stone tools, indicating that the area had been inhabited or used long before the tomb was built.
A surrounding moat encircles the mound, helping to define its overall structure and providing important evidence for understanding its original appearance.
The burial facility is a horizontal stone chamber with entrances on both sides of the passage leading into the main chamber. Its entrance faces south. The surviving structure measures approximately 9.36 meters in total length and consists of a burial chamber and an entrance passage.
The principal dimensions are as follows:
Total surviving length: approximately 9.36 meters.
Main burial chamber: 3.86 meters long, 1.93–2.15 meters wide, and 2.65 meters high.
Entrance passage: 5.50 meters in surviving length and 1.41–1.80 meters wide.
The chamber was constructed using granite blocks. The walls of the main burial chamber consist of six to nine courses of stone, while the entrance passage has two to four courses. Large stones form the lower sections of the rear and side walls, with smaller stones stacked above them.
The floor of the main chamber is covered with gravel measuring approximately 10–25 centimeters across. Beneath the gravel lies a carefully designed drainage channel that runs around the rear and side walls of the chamber. The channel joins near the entrance to the main chamber and continues beneath the entrance passage and the blocking stones that once sealed the entrance.
This drainage arrangement demonstrates the practical engineering incorporated into the tomb’s construction, helping to manage water within the underground burial space.
Although the stone chamber had been disturbed by grave robbers, archaeological excavations uncovered several valuable artifacts associated with its original use. These included earrings, small knives, horse fittings, Sue ware pottery, and Haji ware pottery.
The Sue ware finds included five covered cups and two tall cups without lids. Such objects provide clues about burial customs and the material culture of the people who lived during the late Kofun period.
Fragments of clay coffins were also discovered. These belonged to three types of turtle-shell-shaped terracotta coffins made from Haji ware clay. The presence of several coffin types suggests that more than one individual may have been buried at the site.
Some of the most distinctive discoveries date from the site’s reuse as a Buddhist hall during the medieval period. These include gilt-bronze Buddhist statues, fragments of molded clay Buddhist figures, flower vases, ritual incense burners, small ritual offering vessels, glazed stoneware bowls, and Haji ware dishes.
The objects date broadly from the Kamakura period (1185–1333) to the Muromachi period (1336–1573). They offer valuable insight into the religious practices and Buddhist culture that flourished at the site centuries after the original burial.
Based on archaeological evidence and the typology of the excavated materials, Hotoketsuka Kofun is thought to have been constructed around the end of the 6th century, during the late Kofun period. Its estimated date corresponds to the TK209 pottery classification period.
This was a significant era in the history of Ikaruga. According to traditional chronology, construction of the Ikaruga Palace associated with Prince Umayado, better known as Prince Shotoku, began in 601, during the ninth year of Empress Suiko’s reign.
The approximate date of the tomb has led researchers to consider whether its occupants or the people responsible for its construction had connections with Prince Umayado and the ruling family associated with the Upper Palace. However, a direct relationship has not been conclusively established.
Hotoketsuka Kofun has experienced several distinct phases in its long history. Originally built as a burial mound, it was later adapted for Buddhist worship during the medieval period. The large number of Buddhist artifacts recovered from the site reflects this transformation and reveals how an ancient funerary structure could acquire a new religious role over time.
These discoveries make the site particularly valuable for understanding both the burial practices of ancient Japan and the development of Buddhist belief in the Ikaruga area.
On March 21, 1997, Hotoketsuka Kofun was designated a Prefectural Historic Site of Nara in recognition of its archaeological and historical importance. Today, it is carefully protected as a valuable cultural property, and access to the interior of the stone burial chamber is restricted.
The mound stands in a quiet hilly area of Ikaruga Town, not far from Horyu-ji Temple. It can be considered as part of a visit to the region’s remarkable collection of ancient temples and archaeological sites.
Because access may be restricted to protect the remains, visitors are advised to check local guidance before planning a visit. Even from outside, the site offers an opportunity to appreciate the archaeological heritage of Ikaruga and reflect on the many layers of history preserved in its landscape.
Hotoketsuka Kofun is a valuable historical site that reveals the changing uses of a place over more than a millennium. Its square mound, carefully constructed stone chamber, drainage system, and diverse collection of artifacts provide important evidence of life and burial customs in ancient Japan.
The later discovery of Buddhist statues and ritual objects adds another dimension to its story, connecting the burial traditions of the Kofun period with the religious life of medieval Ikaruga. For visitors interested in Japanese archaeology, ancient history, and the cultural landscape surrounding Horyu-ji Temple, Hotoketsuka Kofun offers a fascinating glimpse into the region’s past.