Imashirozuka Kofun: Japan's Only Walkable Imperial Tomb

Hidden in the residential neighborhoods of Takatsuki City, Osaka Prefecture, lies one of Japan's most extraordinary archaeological treasures — Imashirozuka Kofun. This massive keyhole-shaped burial mound, believed to be the true resting place of the 26th Emperor Keitai (died 531 AD), holds a unique distinction: it is the only imperial tomb in Japan that the public can freely enter and explore. While nearly all other imperial burial mounds across the country are sealed off by the Imperial Household Agency, Imashirozuka Kofun welcomes visitors to walk its ancient paths, climb its tree-covered mound, and stand in the presence of over 200 meticulously reconstructed haniwa clay figures — an experience available nowhere else on earth.

A Monumental Tomb from the 6th Century

Imashirozuka Kofun is a front-square, rear-round (zenpō-kōen-fun) burial mound constructed in the early 6th century, during the late Kofun period. The central mound stretches 190 meters in length, while the total site — including its impressive double moat system — measures approximately 350 meters long and 340 meters wide. This makes it the largest burial mound in the entire Yodo River basin and one of the most significant tombs built during that era.

The tomb is situated near the center of the Mishima Plain in northern Osaka, an area that has been home to human settlements since prehistoric times. The region, historically known as "Mishima," contains roughly 700 burial mounds spanning from the early Kofun period through the Asuka period, making it a veritable microcosm of Japan's ancient funerary culture.

The True Tomb of Emperor Keitai

Based on the mound's shape, the dating of excavated haniwa clay figures, and evidence found in classical texts such as the Kojiki (Record of Ancient Matters) and Nihon Shoki (Chronicle of Japan), scholars have reached a strong consensus that Imashirozuka Kofun is the authentic mausoleum of Emperor Keitai — the 26th sovereign of Japan and the great-grandfather of Prince Shōtoku.

Interestingly, the Imperial Household Agency officially designates a different tomb, the Ōta Chausuyama Kofun located 1.3 kilometers to the west in Ibaraki City, as Emperor Keitai's mausoleum. However, archaeological evidence has shown that Ōta Chausuyama dates to the mid-5th century — significantly earlier than Emperor Keitai's reign. This historical misidentification is precisely what makes Imashirozuka Kofun accessible to the public today: because it was not recognized as an imperial tomb, it was never placed under the Agency's strict access controls, allowing decades of groundbreaking archaeological research and, eventually, the creation of an open public park.

Why Was It Designated a National Historic Site?

Imashirozuka Kofun was first designated as a National Historic Site of Japan in 1958, recognizing it as an irreplaceable cultural heritage that chronicles Japan's ancient history. The designation was expanded in 1991 to include the Shinike Haniwa Production Site, and again in 2006 to incorporate the northern sections of the tomb.

The site's extraordinary value lies in several factors:

• It is the largest burial mound in the Yodo River basin, representing the pinnacle of Kofun-period construction in the region.
• Excavations uncovered over 200 haniwa clay figures, including Japan's largest known house-shaped haniwa (approximately 1.7 meters tall), as well as finely crafted warrior, priestess, sumo wrestler, horse, and bird figures.
• The discovery of the haniwa ritual precinct (haniwasaishiku) on the northern inner embankment revealed the actual layout of a Great King's funerary ceremony — the first and only such discovery at an imperial-level tomb in Japan.
• The adjacent Shinike Haniwa Production Site provides a complete picture of ancient haniwa manufacturing, from clay preparation through kiln firing, offering unparalleled insight into the industrial processes that supported royal funerary rites.

Highlights and Attractions

Surrounding Attractions

Takatsuki City offers several other historical and cultural attractions that pair well with a visit to Imashirozuka Kofun:

• Tsugeno Shrine (Torikeno Shrine): A local shrine whose unique approach road passes over the Meishin Expressway via a pedestrian bridge. The hillside behind the shrine contains Torikeno-yama Kofun, an 86.4-meter keyhole-shaped tomb.
• Aman Ruins Park: A large park preserving the remains of a 2,500-year-old Yayoi-period moated settlement, designated as a National Historic Site. Located about 15 minutes on foot from JR Takatsuki Station.
• Takatsuki Castle Historical Park (Shiroato History Museum): Exhibits covering the medieval and early modern history of the Takatsuki area.
• Settsu-kyō Gorge: A scenic natural gorge in northern Takatsuki, perfect for hiking and enjoying seasonal foliage.

Seasonal Highlights

Imashirozuka Kofun is beautiful throughout the year, but each season brings its own charm. Spring brings cherry blossoms to the park's green spaces, while the fresh foliage of early summer creates a lush canopy over the mound's woodland paths. Autumn transforms the deciduous trees into a spectacular display of gold and crimson. August 20th is locally designated as "Haniwa Day," when special events and activities related to haniwa culture are organized at the site. The annual "Hani-Cotto" festival celebrates the area's ancient heritage with markets, workshops, and community activities.