How can international law become genuinely global when its frameworks remain Eurocentric? This volume presents the first systematic account of Japanese international legal theory edited by Japanese scholars, offering perspectives from a tradition that has navigated between Western modernity and its own experiences for over a century. The book examines thirteen influential Japanese scholars whose theoretical contributions challenge conventional assumptions about international law's foundations. It traces their intellectual journeys across six historical periods, from nineteenth-century debates over sovereignty and civilisation to contemporary theories of normative multilateralism. The volume demonstrates how scholars positioned outside international law's Western centre developed sophisticated frameworks addressing fundamental questions: How can legal traditions communicate across difference? What happens when seeking common ground reproduces existing hierarchies? The editors propose 'conversation' as an alternative mode of engagement--one that respects incommensurability (the recognition that some differences cannot be reconciled) while enabling continuous productive exchange. Through detailed intellectual biographies, the contributors reveal how Japanese theorists strategically employed legal positivism, articulated transcivilisational perspectives, and developed concepts of international administrative law that addressed the structural limitations of Western-centric approaches. Addressed at scholars of international law, legal theory and comparative legal traditions, this volume indicates a future direction that the discipline builds on genuinely reciprocal exchange where diverse perspectives can coexist productively without hierarchical integration.