Lake Shōji is the smallest of the Fuji Five Lakes in terms of surface area, and third deepest, with a maximum water depth of . Its surface elevation of is the same as for Lake Motosu and Lake Sai, confirming that these three lakes were originally a single lake, which was divided by an enormous lava flow from Mount Fuji during an eruption from 864-868 AD. The remnants of the lava flow are now under the Aokigahara Jukai Forest, and there is evidence to indicate that these three lakes remain connected by underground waterways.