Researchers have unearthed a shield-shaped bronze mirror and massive iron sword in an ancient kofun burial mound here, unprecedented discoveries of their kind in Japan.

The unusually shaped mirror and sword of more than 2 meters were discovered at the Tomiomaruyama kofun, Japan’s largest round kofun, which was created in the second half of the fourth century.

The Nara Municipal Buried Cultural Properties Research Center, which excavates and researches kofun, and the Nara prefectural Archaeological Institute of Kashihara, which assists in the excavation, announced the discoveries on Jan. 25.

The Nara center started excavating the Tomiomaruyama kofun in fiscal 2018.

During the current fiscal year, experts excavated a part of the kofun called "tsukuridashi," which is a projected part in the middle portion of the burial mound, and found a burial facility housing a 5-meter-long wooden coffin.

The experts discovered an iron sword and a bronze mirror in the clay that covered the coffin.