With the establishment of a Swiss legation in Tokyo in 1920, neutral Switzerland became uniquely placed to gather first-class intelligence on Japan and the region Japan dominated before and during World War II. The documents from the Swiss Federal archives reveal intelligence collected on Japan, China, Russia and the other parts of East Asia. Based on the communications between the Swiss government in Berne and its diplomats and agents in Tokyo, the documents cover a huge area from Arctic Siberia to the north of Australia. The documents give insight into international politics during a very turbulent period of modern history and demonstrate that Switzerland's need for first-class intelligence created for it the role of an extraordinary "thinking post" in world politics. The author sets the context and provides notes and commentary on the documents.