Design
A one-group pretest–posttest trial was conducted using a mixed-method design. Participants were assessed for outcomes using self-administered questionnaires at baseline (T1), post-intervention (T2; the day after T1), and one month after program completion (T3). The paper questionnaires were distributed and collected by the principal researcher. Group interviews (with some individual to accommodate schedules) were conducted by the principal researcher at T3 for process evaluation (time span per person was 12–21 min). The intervention and data collection were conducted between March and December 2022. This project was registered in the Clinical Trial Registry (UMIN 000041743; 09/09/2020).