There are many ancient tombs in Gunma Prefecture. Kannonyama Kofun is one of them.
It is a 100-meter-long tomb in the form of a keyhole-shaped burial mound. It was built in the late 6th century, more than 1,400 years ago. It is the grave of a person who ruled the area now known as Takasaki City.
Some of the artifacts excavated from the Kannonyama Tumulus are designated as national treasures and are housed at the Prefectural Museum of History in Gunma no Mori.
Stone chambers in ancient tombs are usually already dug out, and in most cases the items that were supposed to be stored inside have been stolen. Fortunately however, the tomb thief was unable to dig out the stone chamber of this tomb because it had collapsed, and the items stored by the tomb owner at the time were unearthed exactly as they were. This is extremely rare in Japan.
https://www.pref.gunma.jp/03/x4510004.html
