Baseball’s place in the relationship between Japan and the United States is the focus of Diamond Diplomacy, a documentary directed by Yuriko Gamo Romer. Presented at a screening ahead of its official Japanese premiere at the Tokyo International Film Festival, the film examines 150 years of shared sporting history alongside questions of race, politics and national identity.
Romer, who was born in Tokyo and grew up in the United States, begins with an American educator’s introduction of baseball to Japan in 1872. The documentary follows its spread through schools, the emergence of professional teams and Japanese players’ eventual arrival in Major League Baseball. Author Robert Whiting, an interview subject, discusses how approaches associated with martial arts helped shape the Japanese game’s emphasis on perfection.
Although Shohei Ohtani’s success has given the subject renewed relevance, Romer said the timing was accidental. Speaking before the premiere, she explained that research began 12 years earlier and that financing required years of earning and raising money. The production secured a $600,000 National Endowment for the Humanities grant, but more than half of that funding was cancelled in April 2025 amid DOGE cuts. Former American diplomat Glen S. Fukushima subsequently supplied $300,000, allowing the documentary to be completed.
Archival footage captures the crowds drawn to Babe Ruth’s 1934 visit with an American League all-star team. The visitors played against and alongside Japanese players as political tensions increased ahead of war. The film also addresses baseball among Japanese-Americans held in internment camps during World War Two, a subject Romer previously explored in Baseball Behind Barbed Wire, and the sport’s role in resisting prejudice after the war.
Tours of Japan by Negro League teams provide another perspective on race and baseball. Players often received better treatment there than in the United States. Japanese hosts praised their humility, respect and sportsmanship, contrasting those qualities with what they described as arrogance among visiting white teams.
A central figure is Masanori “Mashi” Murakami, who became Japan’s first MLB player at 19. His September 1964 debut came for the San Francisco Giants against the New York Mets at Shea Stadium, and his teammates included Willie Mays. Murakami describes whistling Sukiyaki to settle his nerves before games. After the screening, he said his interest in visiting America originally came from watching the cowboy drama Rawhide.
Murakami also emotionally recalled confronting an umpire over a pitch he believed was a strike. Later, a chef at a Japanese restaurant congratulated him. The chef explained that Japanese people had felt pressure to be deferential toward Americans since the war and that seeing Murakami stand up for himself had made him proud.
The documentary also considers Americans who joined Japanese teams, including the difficulties some faced with demanding training and unfamiliar customs. Strand Releasing acquired Diamond Diplomacy for North America, while Wondergenic picked it up for Japan.
