Combined archaeobotanical and archaeological data from Middle Yayoi (fourth century BCE–first century CE) cultural layers of the Maenakanishi site (36°08′55″ N, 139°24′08″ E) in northern Saitama Prefecture indicate that rice was less significant as everyday food, but played an important role in ritual practices and in strengthening social stratification at the studied settlement site. The results further suggest that the crop was used in feasting performed in context of pillared buildings that were often large and occupied a spatially separated central location within a settlement. We propose that these pillared buildings were residences of political/religious leaders, who directed these rituals related to agricultural production and worship of elite ancestors. Such ritual practices were likely introduced to Japan from continental East Asia as part of the ‘Yayoi package’ and conducted for empowerment and labour mobilisation.