After the ‘opening’ of Japan in 1853—54, the international system began to change from the limited, traditional European ‘concert of nations’ to a ‘comity of nations’, proclaiming universal norms and values. Participants in the first Hague Peace Conference — called by the Russian Tsar, Nicholas II — therefore included the USA, China, Japan, Persia, Siam (Thailand) and Turkey The conference marked the early stages of todays International Court of Justice and the United Nations Organization. Although for the Japanese in 1899 the revision of the unequal treaties had priority, they also placed hope in the conferences. Japan was ready, if the Western powers would agree among themselves, to join efforts for disarmament and the peaceful settlement of international disputes, including obligatory arbitration — major subjects discussed at the conferences. Unlike Germany, which had almost boycotted the conferences from the start, the Japanese foreign ministry, in spite of its reserve, took the proceedings very seriously, and was prepared to participate fully. Not least in view of the economic, social and political consequences of war, and alerted by politicians, diplomats, international law scholars, and a broad and active peace movement, nation states considered adopting legal process instead of the traditional call to arms to resolve their differences. Publications like those of Jean de Bloch about the costs and effects of future wars were receive4 in Japan also. A comparison of these trends and contemporary records in the Japanese archives shows that Japan was a conscientious participant that clearly recognized the merits of the ideas discussed at The Hague.