The uptake of policies and recommendations to promote physical activity (PA) in American schools has been slow. It can be useful to investigate international contexts where school-based PA promotion has had more success and consider whether facilitative factors have transferability to American schools. This study employed a social ecological perspective to examine the school-based PA opportunities for Grade 2 students in Japan and the factors influencing these opportunities. Observations in five public schools, relevant documents, and interviews with teachers, principals, and district and ministry officials were analyzed using constant comparison. Findings showed multiple PA opportunities existed in daily routines and throughout the year. Government policy had a downstream influence on all lower levels of the education system. Many of the PA opportunities Japanese schools provided align with American recommendations, but different educational priorities between Japan and the United States might make implementing these opportunities more challenging in American schools.