Study participants
Requests for research participation were sent to 322 public elementary schools in three Japanese prefectures. Only schools that were willing to cooperate were included in the study.A maximum of 10 schoolteachers participated from each school. The inclusion criterion was full-time schoolteachers, and the exclusion criteria were difficulty in understanding Japanese and being unable to conduct web surveys or operate video watching. The sample size was determined with reference to 50-min video programs for improving schoolteachers’ mental health literacy in Japan [