The COVID-19 pandemic has drastically changed our daily lives in terms of eating, learning, working, and leisure time. So far, Japan has experienced eight waves of widespread infection and three emergency declarations but has coped with the crisis without mandatory lockdowns, behavioral restrictions, and mandatory mask-wearing that were seen in other countries. The response has mainly been an encouragement of behavioral changes in our daily lives. In this paper, we observe through “consumption big data” the initial disruption, the adaptation period, and the change to a new normal. We use point of sale (POS) data from supermarkets, convenience stores, home centers, drugstores, and consumer electronics mass merchandisers, as well as data from household bookkeeping applications, for the two years from January 2020 to December 2021. The POS data were used to observe item-level sales trends, while the household bookkeeping application data were used to observe trends in service expenditures and the prevalence of cashless payments. This made it possible to comprehensively understand the changes in consumer behavior during the pandemic.