The coastal area of Tokyo Bay, stretching from Yokosuka City in Kanagawa Prefecture to Futtsu City in Chiba Prefecture, has the densest concentration of shell mounds in Japan. These also include some of the largest shell mounds in the country, rivaling the Kasori Shell Midden in Chiba City. The reason behind the formation of many of the shell mounds in this region, including the largest, is related to the occurrence of climate change and climate variability on a global scale.