Shirahatazuka Heritage Park

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• Park
• Open 24 hoursEvery day
• 4 kmfrom Adachi center
• 3.7 / 5158 reviews
• Adachi

The last mound of a lost graveyard

This neighbourhood, Higashi-ikō in Adachi's low northern reach, was once dotted with burial mounds. Records and old Edo-period maps show a group of tumuli along the natural levees beside the Keja River—among them Suribachi-zuka (the "Mortar Mound"), Kabuto-zuka ("Helmet Mound") and Fuyama-zuka ("Boat-Mountain Mound")—together forming what is now called the Ikō (or Shirahatazuka) kofun group. From one of these, the Mortar Mound, excavators recovered figure and horse haniwa and cylindrical clay vessels, helping date the cluster to roughly the 5th–6th centuries.↗↗↗

Almost all of them vanished. As the wartime and postwar years reshaped Adachi into dense suburbia, land-readjustment schemes in the 1960s levelled the surrounding mounds for housing. Only Shirahatazuka was spared. Recognising its rarity, Tokyo designated it a Historic Site in February 1975, and recent surveys have left it the only genuinely surviving kofun in the whole ward—a small, green survivor of a vanished ancient graveyard.↗↗↗

Why a burial mound is called the "White Flag Mound"

The kofun predates written local history, but its name comes from a far later legend set down in the Edo-period provincial gazetteer Shinpen Musashi Fudokikō. As the story runs, the samurai lords Minamoto no Yoriyoshi and his son Yoshiie, marching north to put down a rebellion in the 1060s, halted at this spot; after a hard-fought victory, Yoriyoshi raised a white flag—shirohata—on the mound, and so the hill became the "White Flag Mound," Shirahata-zuka.↗↗↗

The tale layers the Heike-era warrior lore of the Eastern Provinces Campaign onto a tomb some five centuries older, and the park's designers leaned into that double history: a stone stele quoting the Fudokikō stands on the grounds to recall the legend behind the name.↗↗↗

What to notice in the park

The mound itself is a soft, broad hill of earth crowned with trees, ringed by a shallow moat that hints at how it once looked in open lowland. Visitors walk around it rather than over it—the burial chamber is unopened and unexcavated, and its occupant and grave goods remain a mystery, which is part of the quiet romance of the place.↗↗↗

Scattered about the grounds are replicas of haniwa, the terracotta figures that once ringed kofun in rows. There are four friendly-looking types—a soldier-like figure, a horse, a house shape and a boat-shaped figure—copied from finds at other mounds rather than from Shirahatazuka itself. Deliberately quirky and endearing, they were installed to make passers-by curious about the buried past; they have become the park's most charming draw, and a favourite stop for kofun enthusiasts.↗↗↗

Nearby stands a stone monument engraved with ancient ideograms marking the four cardinal directions—East, West, South and North—acting like an old-world compass set into the green. And because the ward planted the grounds with the Aki-no-nanakusa, the "Seven Flowers of Autumn" of classical poetry, each with its related tanka verse posted beside it, a visit in the cooler months adds a seasonal, literary touch to the archaeological one.

Pairing it with the neighbourhood's other ancient sites

For a fuller picture of Kofun-period life in this lowland, the park makes an easy pairing with nearby sites. About ten minutes' walk further is Ikō Heritage Park (伊興遺跡公園), a reconstructed settlement from the same era with pit-dwellings and a square-moated grave, plus a small exhibition hall displaying ritual and everyday artefacts excavated from the Ikō area—the very community that the people buried around Shirahatazuka may have belonged to. Not far away, the old Ikō Hikawa Shrine, known locally as Fuchi-no-miya, marks the wetland pools where that settlement once stood.↗↗↗