In these notes, we share our experiences of researching and co-authoring a recent article on the comparative treatment of Japanese residents and internees by the Soviet Union and the People's Republic of China in the first decade following World War II. This collaboration started from our surprising realization that despite their shared ideology and friendly relations, Moscow and Beijing adopted different approaches to dealing with Japanese citizens under their control. Here we recount the decade-long path our collaborative research took as we consulted multilingual government archives, survivor interviews, and memoirs to reconstruct the early years of Sino–Soviet cooperation and to argue for a more comprehensive, empirical approach to the evolution of early Cold War international relations in East Asia. The article, ‘“Japan Still Has Cadres Remaining”: Japanese in the USSR and Mainland China, 1945–1956‘, was published by the Journal of Cold War Studies in its Summer 2022 issue.