Dataset of social psychology in Japan during COVID-19: A 30-wave panel (January 2020-March 2024)

This data article describes a 30-wave longitudinal online survey of adults in Japan that tracked psychological and social responses to COVID-19 from January 2020 to March 2024. Wave 1 recruited 1248 participants via a nationwide crowdsourcing platform; invitations to wave t + 1 were sent only to those who responded at wave t. To mitigate attrition, an additional cohort of 600 participants was added at Wave 13 under the same procedures. Data collection moved from 2-week to 1-month intervals early on to a regular bimonthly schedule from May 2020. Surveys were self-administered in Japanese. Repeated measures cover interest in COVID-19, risk perception (dread, unknown), infection-prevention behaviors, attitudes toward public-health policies, intergroup attitudes, perceived social disruption, and psychological distress, with time-specific modules added as policy and epidemiological contexts evolved; wave-by-wave availability and exact wording are documented in the codebook and questionnaires (the codebook provides English translations of all items). The dataset is intended for reuse in within-person panel analyses (e.g., fixed-effects, growth-curve, cross-lagged), event-aligned designs around policy milestones, and heterogeneity analyses by age, region, and cohort (baseline vs top-up), and supports replication and pedagogical applications.