--- title: "Atomic Bomb Game: two Go masters finished their 1945 title match near Hiroshima hours after the blast" url: https://badiyaa.com/atomic-bomb-game-go-hiroshima-1945/ published: 2026-11-12T12:09:00+00:00 modified: 2026-11-12T12:09:00+00:00 section: History publisher: Badiyaa --- # Atomic Bomb Game: two Go masters finished their 1945 title match near Hiroshima hours after the blast In the Atomic Bomb Game of August 6, 1945, Go players Utaro Hashimoto and Kaoru Iwamoto resumed play near Hiroshima and finished that evening. On the morning of August 6, 1945, two of Japan’s best Go players sat down in a house on the edge of Hiroshima to finish a championship game. At 8:15 a.m. the atomic bomb exploded about 5 kilometers (3.1 miles) away. After a lunch break they went back to the board, played on, and finished that evening. Utaro Hashimoto, holding White, won by five points. Go players still call it the Atomic Bomb Game. It was game two of the third Honinbo title match, Japan’s most prestigious Go championship of the day, and its survival turned on a decision made by the local police weeks earlier. ## Why the game was outside the city Game one had been played from July 23 to 25 in central Hiroshima. After propaganda leaflets were dropped over the area, the police advised the organizers to move the next game farther out, and it was set in the suburbs. The three-day game began on August 4. The players owed their lives to that move, as the biography of challenger Kaoru Iwamoto puts it. On the morning of the third day, Hashimoto and Iwamoto had replayed the moves to the adjourned position and were about to continue when the bomb went off. The blast disrupted play, damaged the building and left some of those at the match hurt. A diagram of the game shows the board as it stood at move 106, the point it had reached when the bomb exploded. ## Who were the two players - **Utaro Hashimoto** (1907-1994), born in Osaka, turned professional in 1922 at 15. He was the defending Honinbo, having won the title in 1943. - **Kaoru Iwamoto** (1902-1999), born in Masuda in Shimane Prefecture, learned Go from his father while living in Busan, Korea. He had quit the game in 1929 to grow coffee in Brazil, came back two years later when the farm failed, and won the Oteai tournament in 1935. ## What a Honinbo match is The Honinbo name comes from the old Honinbo house of Go, one of the schools set up under the Tokugawa shoguns. By the 1940s it had become a title decided by a challenge match: the holder defends against a qualifier over a series of long games, each spread across days, with play adjourned overnight. That format explains the odd timeline of August 6. The players were not mid-move when the bomb fell; they were resetting the board for the final day. ## How the match ended The war ended nine days later, and the match was not over. Play resumed after the war and finished level at three games each. A three-game playoff in 1946 went to Iwamoto, who won the first two and took the title, playing under the name Honinbo Kunwa. Hashimoto won the Honinbo back in 1950 and kept it in 1951. Both men shaped Go long after 1945. Hashimoto founded the Kansai Ki-in, a Go association based in western Japan, in 1950, and reached 9-dan in 1954. Iwamoto’s home served as a temporary base for the Nihon Ki-in after bombing burned out its headquarters, and in 1948 he became the association’s president. Iwamoto then became one of Go’s great ambassadors to the West. He spent 18 months in New York in 1961 and 1962 teaching the game, and in 1986 he set up the Iwamoto Foundation with 530 million yen. Over the years it became the main backer of Go clubs in five cities on three continents, from Amsterdam and London to Seattle, New York and São Paulo. In 2014 the Nihon Ki-in and the American Go Association created the Iwamoto North America Foundation for Go in his name. The year 1945 ran through other Pacific stories on our [History section](https://badiyaa.com/category/history/), including how the [Navajo Code Talkers sent 800 error-free messages at Iwo Jima](https://badiyaa.com/navajo-code-talkers-world-war-ii/) that February. Iwamoto retired in April 1983 and lived to 97. The game he lost on August 6, 1945, by five points, is still one of the most retold in Go. ## Further reading - [Wikipedia: List of Go games (Atomic bomb game)](https://en.wikipedia.org/wiki/List_of_Go_games) - [Wikipedia: Kaoru Iwamoto](https://en.wikipedia.org/wiki/Kaoru_Iwamoto) - [Wikipedia: Utaro Hashimoto](https://en.wikipedia.org/wiki/Utaro_Hashimoto) *Image: Dietmar Rabich, CC BY-SA 4.0 via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*