Early burial mounds of the 3rd century AD made use of natural hill forms, but in the 5th century, mounds were artificially constructed on flat land, with moats around them. The most common ground-plan was a combination of circular and triangular parts, termed 'keyhole-shaped' by Western archaeologists.

The graves themselves, with stone walls, were situated towards the top of the mound. Iron weapons, bronze mirrors, and jade and jasper ornaments were placed inside. The chamber was then closed from above and the shaft filled in with earth. Ceramic objects known as haniwa were set around the surface of the mound, representing houses, people and animals. It is assumed that members of the ruling families were buried in these grand tombs. Some remain off-limits to archaeologists as their occupants are believed to be distant ancestors of the Japanese imperial family.

The largest burial mound in Japan is in the city of Sakai, near Osaka, measuring 27m high and almost 487m long, with three moats. It is thought to have been the tomb of the Emperor Nintoku, who reigned in the 4th century. In the late 5th to early 6th centuries a form of tomb common in Korea was used in Japan. In these tombs a horizontal corridor allowed for re-entry and multiple burials of family members.