During this period, the Kantō region was inhabited by the Jōmon people, many of whom lived in coastal settlements.

The middens associated with such settlements contain bone, botanical material, mollusc shells, sherds, lithics, and other artifacts and ecofacts associated with the now-vanished inhabitants, and these features, provide a useful source into the diets and habits of Jōmon society.

The Natsushima site is located on what was once an island in Tokyo Bay, but which is now surrounded by reclaimed land.

The midden is located at the eastern end of the former island, at an elevation of 50 meters above the present sea level.

Other artifacts in the midden included stone weapons and stone tools, bone weapons and tools, fishing hooks made from shell, and shell ring jewelry.