This data set contains absolute counts of carbonised seeds of wild and cultivated plants and rice chaffs as well as floated litres of sediment per sample from the Middle Yayoi culture layers of the 2018 survey sections 2 and 3 of the Maenakanishi site (Kumagaya City, Saitama Prefecture, Japan). The analysed sediment samples represent ten hearths deposits collected during archaeological excavation from eight different house pits that were treated by bucket flotation to extract carbonised plant remains. The derived samples were analysed using a stereo microscope.