Qualla: Dairizuka Kofun

Dairizuka Kofun: Introduction

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Motokoka, CC BY-SA 4.0. From the air, it looks like a giant keyhole pressed into the earth -- one end perfectly circular, the other squared off in a clean rectangle, both rising 13 meters above the estuary lowlands of the Koito River. The Dairizuka Kofun stretches 144 meters from end to end, the largest keyhole-shaped burial mound in all of southern Kanto. Sixteen centuries of typhoons, earthquakes, and rice paddies have worn its edges, but the basic shape remains unmistakable, a monument to a ruler whose name has been lost to time but whose power was literally carved into the landscape of what is now Futtsu, Chiba Prefecture.

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Image: Motokoka | CC BY-SA 4.0

Dairizuka Kofun: A Kingdom at the Crossroads

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Saigen Jiro, CC0. The Koito River valley was not chosen by accident. Where the river empties into Tokyo Bay on the central Boso Peninsula, the ancient Kingdom of Sue controlled one of the most strategic crossroads in early Japan. From here, ships could reach the Miura Peninsula across the bay and ...

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Image: Saigen Jiro | CC0

Dairizuka Kofun: The Keyhole and Its Guardians

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Alexrk2, CC BY-SA 3.0. The tumulus was constructed in two tiers, its slopes once armored with fukiishi -- carefully placed stones that prevented erosion and gave the mound a gleaming, fortress-like appearance. A moat originally encircled the entire structure. Most striking were the haniwa, the clay fig...

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Image: Alexrk2 | CC BY-SA 3.0

Dairizuka Kofun: Swords, Mirrors, and a Whistling Arrow

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit User:Xser21 User:掬茶 User:Shadow Fox User:Kentagon User:くろふね ja:利用者:Skink User:Yamato-i, CC BY-SA 4.0. When Tokyo Imperial University excavated the Dairizuka Kofun in 1906, they found two stone burial chambers aligned along the mound's central axis within the circular rear section. The eastern chamber, 5.75 meters long, held two sets of human remains alongside five iron swords, a ...

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Image: User:Xser21 User:掬茶 User:Shadow Fox User:Kentagon User:くろふね ja:利用者:Skink User:Yamato-i | CC BY-SA 4.0

Dairizuka Kofun: Legends and the Yamato Hero

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit 京浜にけ at Japanese Wikipedia This photo was taken with Canon PowerShot G9, CC BY-SA 3.0. Local tradition offers two candidates for the tomb's occupant, neither definitively proven. The Kujiki chronicle records that the Kingdom of Sue was governed by a kuni no miyatsuko, a regional lord appointed by the Yamato court. Given that Dairizuka is the largest keyhole kofun i...

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Image: 京浜にけ at Japanese Wikipedia This photo was taken with Canon PowerShot G9 | CC BY-SA 3.0

Dairizuka Kofun: A Monument Preserved

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Motokoka, CC BY-SA 4.0. The Japanese government designated Dairizuka Kofun a National Historic Site in 2002, expanding the protected area in 2009. The mound rises today from a quiet residential neighborhood in Futtsu, a ten-minute walk from Aohori Station on the JR East Uchibo Line. It is a strangely do...

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Image: Motokoka | CC BY-SA 4.0