Nishitonozuka Kofun is a large keyhole-shaped burial mound located in Nakayama-chō, Tenri City, Nara Prefecture. It is an important component of the Nakayama group within the Yamato Kofun complex, one of the region’s significant concentrations of ancient tombs.
The Imperial Household Agency officially identifies the mound as Fusumada-no-Misasagi, the imperial mausoleum of Princess Tashiraka, consort of Emperor Keitai, traditionally counted as Japan’s 26th emperor. A designated worship area has been established outside the mound, allowing visitors to pay their respects while viewing the historic site from the permitted area.
Nishitonozuka Kofun was constructed on a hillside along the eastern edge of the Nara Basin. Tōtonozuka Kofun lies nearby to the east. Both mounds occupy relatively high ground within the Yamato Kofun complex and offer a setting associated with sweeping views across the basin.
The mound measures approximately 230 meters in total length, making it one of the largest burial mounds in the Yamato Kofun complex. Its keyhole-shaped layout consists of a rounded rear section and a projecting rectangular front section, with additional raised platforms incorporated into the design.
The principal dimensions are as follows:
Rear circular section: Approximately 140 meters in diameter and 16 meters high on the eastern side. It was built in three tiers on the east and four tiers on the west.
Front rectangular section: Approximately 130 meters wide and 12 meters high on the eastern side. It was built in one tier on the east and two tiers on the west.
Raised rectangular platforms: Additional platforms were constructed on both the rear and front sections. The platform on the rear section measures approximately 25 by 26 meters and stands about 3 meters high.
The mound was built at right angles to the slope of the natural terrain, resulting in an asymmetrical shape. A broad, flat area known as an “apron” has also been identified along the western side, forming a distinctive feature of the site.
Stones known as fukiishi were used to cover the surface of the mound, a technique commonly associated with ancient Japanese burial mounds. Excavated materials include distinctive pedestal-shaped pottery, haniwa clay figures, special jar-shaped haniwa, and cylindrical haniwa with stepped rims.
These artifacts are important evidence for understanding the early Kofun period and the development of burial customs during the formation of the Yamato polity. Finds from the site may be displayed in museums in Nara Prefecture, where they help explain the craftsmanship and ceremonial practices of ancient communities.
Nishitonozuka Kofun is generally dated to the latter half of the third century, during the early Kofun period. It appears to have been built after Hashihaka Kofun in Sakurai City, another major monument associated with the emergence of early political authority in the Nara Basin.
Its immense size and early construction date have led researchers to consider the possibility that it served as a royal burial mound for a ruler of the emerging Yamato polity. The site is therefore important for understanding the development of political power and the early formation of the Japanese state.
In 1876, during the Meiji period, Nishitonozuka Kofun was designated as the mausoleum of Princess Tashiraka. The site underwent restoration work in 1889 and has since been managed by the Imperial Household Agency. Investigations of the mound’s exterior and surrounding areas have been conducted at various times.
Fiscal year 1989: The Archives and Mausolea Department of the Imperial Household Agency conducted a survey of the mound’s exterior.
Fiscal years 1992–1994: Tenri City Board of Education carried out the second through fourth archaeological investigations.
2012: The Archaeological Institute of Kashihara, Nara Prefecture, conducted aerial three-dimensional surveying, along with an emergency investigation related to evidence of unauthorized digging.
2013: A joint inspection was conducted by 15 archaeological and historical academic societies.
The identity of the person buried at Nishitonozuka Kofun remains a subject of debate. Although the Imperial Household Agency identifies it as the mausoleum of Princess Tashiraka, the estimated construction date in the third century does not correspond with the period in which she is believed to have lived, around the sixth century.
As a result, some researchers favor the theory that Princess Tashiraka’s actual tomb is Nishiyamazuka Kofun, also located in Tenri City. Under this interpretation, Nishitonozuka Kofun may instead be the tomb of a powerful ruler from the third century. Suggested candidates have included Toyo, also known by the names Iyo or Taiyo in different historical interpretations, who is traditionally regarded as a successor to Queen Himiko, as well as Emperor Sujin. However, the identity of the occupant has not been conclusively established.
Nishitonozuka Kofun is under the management of the Imperial Household Agency, and visitors cannot enter the burial mound. The designated worship area provides an opportunity to view the monumental earthwork from outside while respecting the site’s protected status.
The surrounding area is quiet and green, making it a suitable place for a peaceful walk and reflection on Japan’s ancient history. Visiting nearby Tōtonozuka Kofun as well offers a broader understanding of the scale and distribution of the Yamato Kofun complex.
The burial mound is located in Nakayama-chō, Tenri City. From JR or Kintetsu Tenri Station, visitors can travel by bus or taxi. Parking facilities in the surrounding area are limited, so public transportation is recommended.
Tōtonozuka Kofun: A neighboring ancient burial mound that complements a visit to Nishitonozuka Kofun.
Yamanobe-no-Michi: A historic walking route often described as one of Japan’s oldest roads, passing through landscapes rich in ancient tombs, shrines, and rural scenery.
Isonokami Shrine: One of Tenri’s most important ancient shrines, renowned for its long religious history and tranquil grounds.
Nishitonozuka Kofun is an important archaeological monument that preserves clues to the origins of ancient Japanese political power. Its monumental scale, distinctive construction, and uncertain identity make it especially intriguing to visitors interested in the early Kofun period.
Although the mound itself cannot be entered, viewing it from the designated area and exploring the surrounding historic landscape offer a memorable way to connect with the deep history of Nara Prefecture.