Examining 150 years of Japan-US relations through the prism of a common passion for baseball, Diamond Diplomacy deftly interweaves the story of Japanese yakyu with issues of history, geopolitics and race.
Directed by Yuriko Gamo Romer, born in Tokyo but raised in the US, the documentary traces baseball’s 1872 introduction to Japan by an American educator and its integration into the school system, through the development of pro teams and the eventual flow of Japanese players to the major leagues. Along the way were tours to Japan by Babe Ruth – credited, perhaps hyperbolically, for delaying war between the US and Japan – and the importance of baseball for Japanese-Americans, through to the superstar status of Shohei Ohtani.
“People from MLB told me that I had great timing and was making the film at just the right moment with Ohtani’s success,” said Romer at a screening before the film’s official Japan premiere at Tokyo International Film Festival. “But it was just coincidence. I started researching this film 12 years ago and it took me years of making money and raising money to fund it.”
Having landed a $600,000 National Endowment for the Humanities grant, more than half of the funding was cancelled in April 2025 as swingeing DOGE cuts suddenly took effect. Former American diplomat Glen S. Fukushima stepped in with $300,000 that allowed the film to be finished.
Author Robert Whiting, whose books helped introduce the peculiarities of baseball in Japan to the wider world, is one of the documentary’s talking heads.
“Japanese baseball is older than judo,” notes Whiting in the film, going on to suggest that perfectionist methods and obsessive mindsets adapted from martial arts helped mold baseball in Japan.
Masanori “Mashi” Murakami was the first Japanese-born player to play in Major League Baseball.
Tokyo International Film Festival
Footage of Babe Ruth’s 1934 tour leading an all-star American League team shows the wild enthusiasm of huge crowds that turned out to see the visitors as they played against and alongside Japanese players even amidst rising political tensions that would soon culminate in war. Ruth is reported to have thrown all his Japan souvenirs out of his apartment window when he heard the news of the attack on Pearl Harbor.
Romer’s previous documentary Baseball Behind Barbed Wire told how Japanese-Americans interned during World War Two played games inside the camps, which she covers in the new film, along with how baseball was a bulwark against postwar prejudice.
Diamond Diplomacy also tells of Japan tours by Negro League teams, on which the players often found themselves treated much better than they were back home. Their Japanese hosts had praise for the respectfulness, humility and sportsmanship of the Negro League players, something they contrasted with an arrogance commonly displayed by visiting white teams.
Masanori ‘Mashi’ Murakami, who became the first Japanese MLB player aged 19, is at the heart of the film. He made his debut for the San Francisco Giants against the New York Mets at Shea Stadium in September 1964 and played alongside legends including Willie Mays.
In the film, Murakami tells how he used to whistle the tune to Sukiyaki (a huge hit at the time and the subject of the opening film at Tokyo this year) to calm himself before games.
After the screening, Murakami recalled how his desire to go to the US was driven not by a dream of playing in the major leagues but by his love of the cowboy drama Rawhide, which was a huge hit in Japan.
“During one game in San Francisco, an umpire made a terrible call on a pitch of mine that was clearly a strike. I got mad, threw the ball on the ground and the umpire and I ended up squaring up to each other. Afterwards, I went for dinner at a Japanese restaurant and the chef came out and shook my hand telling me how well I’d done. At first, I didn’t understand but he explained that since the war, Japanese people felt they had to be subservient to Americans so he was so proud to see me stand up for myself,” recounted Murakami, becoming emotional at the memory.
The film also looks at American players who came to the Japanese leagues, and the struggles of some to adjust to the brutal training regimes and different customs they encountered.
Diamond Diplomacy was picked up by Strand Releasing for North America and Wondergenic for Japan.