The internal structure of the kofun is not clear, and it appears that it did not have a stone-lined burial chamber, and as the tomb has been robbed in antiquity, the amount of surviving grave goods is minimal. The tomb was opened in 1812 during the Edo period, at which time a bronze mirror with a pattern of dragons was discovered. This mirror is 22.7 cm in diameter and is a Niigata Prefectural Important Cultural Asset. Other known artifacts include one jade magatama and seven cylindrical beads, and it was recorded in Edo period records thats some iron objects had been discovered. From these items, it is estimated that the tumuli dates from the 5th century. During the Edo period, local folklore attributed the tomb to the wife of Minamoto no Yorimasa, Ayame Gozen, hence the kofun's name.
