Cities for Better Health Childhood Obesity Prevention Initiative in JAPAN

The goal of this interventional study is to prevent childhood obesity in children aged 6-12 years in Chiba City, Japan. The main questions it aims to answer are: * Does the multi-component intervention for environments around children reduce the BMI z-score of children aged 6-12 years after one and two years? * Does the multi-component intervention for environments around children improve the health-related quality of life (assessed by KIDSCREEN-10) of children aged 6-12 years after one and two years? Researchers will compare school clusters receiving the intervention to control clusters to see if the intervention package promotes healthy eating, increases physical activity, improves health-related quality of life, and reduces obesity prevalence. Participants will: * Attend elementary schools within participating clusters (either the intervention or control group). * Have baseline data collected, with follow-up assessments after one year and two years. * Potentially participate in school-based programs (nutrition education, physical activity promotion) and community-based initiatives (park activation, supermarkets) if in an intervention cluster. * Have their physical activity and dietary behavior assessed through self-report questionnaires.