From the style of the mound and grave goods uncovered within, archaeologists have dated the kofun to the late 5th or early 6th century AD.

The kofun was excavated in 1935 and 1945, during which time a number of haniwa in the shapes of animals, people and buildings were discovered.

However, it was not until 1947 that archaeologists confirmed that the structure was that of a keyhole-shaped kofun (前方後円墳, zenpō-kōen-fun).

During further excavations held from 1974-1975, more haniwa and the fukiishi stones which originally covered the tomb were uncovered.

[2] The site is about 15 minutes by car from JR East Tōhoku Main Line Mizusawa-Esashi Station.The artifacts uncovered in excavations are preserved at the Isawa Local History Museum.