Silver-inlaid inscribed sword excavated from Eta Funayama Kofun

This silver-inlaid sword was excavated in 1873 from the stone chamber in the rear circular mound of Eta Funayama Kofun, in Nagomi Town, Tamana District, Kumamoto Prefecture. The keyhole-shaped tumulus is believed to have been built between the late 5th and early 6th century and is renowned for the richness of its grave goods.

The blade is a single-edged straight sword bearing a 75-character silver-inlaid inscription on the narrow spine of the blade — considered among the oldest formal written records produced within the Japanese archipelago. Beyond the inscription, both faces of the blade also carry silver-inlaid motifs of flowers, horses, fish, and birds.

The inscription includes the phrase "ruling the realm, King Waka[ta]ke[ru]," with the damaged characters generally reconstructed to read "King Wakatakeru" — a figure widely identified with Emperor Yuryaku.

The same royal name appears in gold inlay on the iron sword excavated from Inariyama Kofun in Saitama Prefecture. The discovery of swords bearing the identical royal name at sites in both eastern Kanto and western Kyushu provided decisive evidence that the authority of the Yamato court extended across a wide area of the Japanese archipelago in the late 5th century.

The Eta Funayama Kofun finds, including this sword, were designated a National Treasure as a set in 1965. The sword is now held by the Tokyo National Museum in Taito City, Tokyo.