The United States–Japan relationship has been shaped by both conflict and cooperation, from racial exclusion and wartime incarceration to the postwar alliance that made Japan one of Washington’s closest partners in the Pacific. Baseball has been woven into this history. Introduced to Japan in 1872, the sport grew from a foreign import into a national passion, surviving war and racial prejudice while becoming an unexpected channel of cultural exchange between the two countries.
Directed by Yuriko Gamo Romer, Diamond Diplomacy traces this 150-year relationship through baseball, moving from Babe Ruth’s 1934 goodwill tour and the wartime experiences of Japanese Americans to the 1949 San Francisco Seals goodwill tour organised during the US occupation of Japan. It then follows the later history of Japanese players in Major League Baseball, including Hideo Nomo, Ichiro Suzuki and Shohei Ohtani. Building on Romer’s earlier short documentary Baseball Behind Barbed Wire, the film uses archival material and interviews to examine how a shared sporting culture could survive periods of war, racism and trade tension and become a form of people-to-people diplomacy.
The documentary had its world premiere at the Mill Valley Film Festival in October 2025 and was subsequently selected for festivals including the Hawai’i International Film Festival. It was also named runner-up for the Library of Congress Lavine/Ken Burns Prize for Film. What makes Diamond Diplomacy particularly compelling is its argument that diplomacy does not happen only through governments and formal negotiations. Baseball becomes a lens through which to see changing attitudes between two societies, from wartime hostility to postwar reconciliation and contemporary cultural exchange. For viewers interested in international relations, history or the political power of sport, the film offers an accessible way into a much larger story about how people can reshape relations between countries.
