In recent years, there has been a growing scholarly interest in conceptualising schools beyond their educational functions, as sites and agents of democracy. Yet this interest is often underpinned by a narrow conception of democracy, focusing solely on schools’ public and social aspects. To capture the democratic potential of schools more fully, this article suggests adopting a deliberative systems approach, which conceptualises democracy as differentiated yet linked sites of democratic communications and views schools as one such site. Using this approach as a broader framework and drawing on the fieldwork conducted in two Japanese schools, this article identifies the condition under which schools can become a meaningful part of deliberative systems. It reveals that schools contribute to deliberative systems when they serve as a bridge between children’s everyday practices and deliberative actions in the public space. In light of the findings, this article suggests conceptualising schools as a ‘mediating space’.