After the middle of the middle Jomon period the number of chipped stone axes increased explosively in the Kanto and Chubu regions; many of these assumed the reed, plectrum or counterweight shapes, and not suitable for 'axes' that were vertically brought down.
縄文中期中葉以降、関東地方や中部地方では打製石斧の数量が爆発的に増加するが、形状は短冊形、撥形、分銅形のものが多く、これらは垂直に打ち下ろす「斧」には向いていない。