Inariyama Kofun stretches 120 meters from end to end, making it the second largest tumulus in the Sakitama Kofun Cluster. From the air, its shape is unmistakable: a circular mound joined to a rectangular platform, forming the distinctive keyhole outline that defines the zenpokoenfun style of burial. Proportionally, it is a one-quarter scale replica of the massive Tomb of Emperor Nintoku in Sakai, Osaka -- the largest burial mound on Earth. That deliberate scaling speaks to a hierarchy of power: whoever built Inariyama was important enough to echo the imperial form, but knew his place in the order. Built in the latter half of the 5th century, it was the first tumulus constructed in the Sakitama cluster, and its proportions became the template for the Futagoyama and Tepployama mounds that followed. A protruding platform called a tsukuridashi juts from its western flank, a rare architectural feature that apparently served as a stage for funeral rituals.

Archaeologists opened the burial chamber in 1968 and found a wooden coffin wrapped in clay, resting on a bed of gravel. Inside lay the personal wealth of a powerful figure: iron swords, a bronze mirror, curved magatama jewels, silver rings, gilded metal fittings, fragments of armor, and horse harnesses. The iron sword that would prove most significant appeared unremarkable under its corrosion -- it was only in September 1978, when X-ray radiography penetrated the rust, that researchers discovered an inscription of 115 gold-inlaid characters -- the longest such inscription ever found in a Japanese kofun. The text gives a date corresponding to either 471 or 531 AD and names the sword's owner as Wowake, listing his ancestors across eight generations. Crucially, it also names "Ohatsuse-wakatakeru-no-mikoto" -- a figure recorded in the Nihon Shoki, Japan's ancient chronicle, as an alias of Emperor Yuryaku. Whether Wowake was a local chief who pledged allegiance to the distant Yamato court or an administrator dispatched from the west remains debated. But the sword proved that the Yamato kingdom's political network extended deep into the Kanto Plain by the late 5th century -- far earlier and more firmly than previously believed.

The mound nearly did not survive to tell its story. In 1937, workers demolishing the forward rectangular portion to use as landfill during swamp reclamation carved away a significant section before anyone intervened. The tumulus deteriorated further over the following decades, its double rectangular moat silting in, its earthen flanks eroding and threatening to collapse. Restoration of a portion of the inner moat began in 1976, but it was not until 2003 that comprehensive restoration work stabilized the mound. A ground-penetrating radar survey in 2016 revealed that additional burial chambers remain unexcavated beneath the surface -- secrets the mound has yet to give up. The excavated artifacts, meanwhile, were designated an Important Cultural Property in 1981 and elevated to National Treasure status in 1983. In 2020, the entire Sakitama Kofun Cluster received designation as a Special National Historic Site, Japan's highest level of protection for archaeological landmarks.

Stand on the summit of Inariyama's circular rear mound, 11.7 meters above the surrounding plain, and on a clear day Mount Fuji materializes on the horizon a hundred kilometers to the southwest. This is not coincidence. The main axis of the tumulus is deliberately aligned toward the sacred peak, a detail that speaks to the cosmological thinking of its builders. Fuji was already a spiritual landmark in the 5th century, and orienting a burial mound toward it would have imbued the site with symbolic power. Below, the flat expanse of the Kanto Plain stretches in every direction -- rice paddies, suburban rooftops, and the meandering course of rivers that once fed the moats. Inariyama Kofun stands as one of several mounds in the cluster, each a monument to a local elite whose world was connected by sword, tribute, and imperial ambition to the centers of power far to the west.