SHIBUSHI, Kagoshima Prefecture--Workers paving a farm road here stumbled on a 1,500-year-old underground tomb containing a large stone coffin, human remains and armor in remarkable condition.

The remains are likely of a local chieftain while the cuirass, a type of breastplate known as “tanko,” is believed to have been a gift from the Yamato imperial court in current Nara Prefecture in appreciation of the leader’s cooperation, the education board of Shibushi city said Jan. 24.

A cuirass known as a “tanko” and preserved in excellent condition, and a stone coffin, left, have been unearthed in Shibushi, Kagoshima Prefecture. (Provided by the Shibushi city education board)

The tunnel-tomb was unearthed during farm road paving work in December.

“It was likely built for a powerful leader in the local region who was directly connected with the Yamato imperial court,” said Tatsuya Hashimoto, a professor of archaeology at the Kagoshima University Museum.

The grave, which is from the Kofun Period (late third to seventh centuries), is one of the largest tunnel-tombs in the Osumi region in eastern Kagoshima Prefecture. It boasts a vertical shaft that is 2.6 meters long, 1.8 meters wide and 1.6 meters deep. The burial chamber is 2.6 meters long, 1.9 meters wide and 90 centimeters high.

This type of construction is unique to the southern Kyushu region. The site has been named the No. 3 Harada Chikashiki Yokoanabo (Harada underground tunnel-tomb).

The skeletal remains are those of a 170-centimeter-tall adult male.

A sword, its scabbard and other items were also found in the pumice stone coffin measuring 2.4 meters. It is 60 cm wide and 50 cm tall.

The tanko is in near-immaculate condition and was standing beside the coffin. The armor measures 35 cm by 40 cm.

More than 20 burial accessories, such as an iron arrowhead, spear and iron ax were discovered.

The tomb features more grave accessories than any other tunnel-tombs in the Osumi region, according to the education board.