1945 · third Honinbo title
Why the Atomic Bomb Game continued after the board was thrown
The Hiroshima bomb exploded while White 106 was being replayed after adjournment. The shock wave scattered the room; people helped one another, restored order, and resumed. The game matters only if disaster is not romanticized.
Utaro Hashimoto (Black) vs Kaoru Iwamoto (White) · 1945.08.04—08.06 · Honinbo title game two · White won by 5 · no komi
War had already moved the game
Police warned against the original Hiroshima-city venue, so play moved to a house in suburban Itsukaichi. On August 6 the players replayed the adjourned position through White 106; the 8:15 blast wave then reached them.
An SGF joins White 106 to Black 107 and cannot show broken glass or a city's suffering. The Nihon Ki-in says play resumed around 10:30 and ended near 16:00. That timeline sets a boundary; it does not turn perseverance into an answer to catastrophe.
A cinematic legend versus a careful timeline
Retellings often attach the explosion to one stone being played. The stronger account says the previous day's position had just been restored through White 106 when the shock arrived.
Resuming can reflect wartime routine, professional duty, and a human need for order at once. We cannot choose one motive for the players.
Why Black 131 is the fork instead of the explosion
The bombing lies between recorded moves but is not a Go candidate. Official commentary instead identifies Black 131 as slack and White 132 as the moment White recovered the initiative.
The article therefore keeps history and analysis distinct: prose documents the gap after White 106; the TreeView asks what Black could have done at 131.
TreeView translates 'slack' into move-order differences
The root is after White 130. The played branch preserves Black 131; three candidates begin from exactly the same board.
Follow several nodes. A slack move may not lose ten points immediately; it often transfers the next meaningful choice to the opponent.
Four ways to use one window
E10 drops Black from about 91.9% and +5.7 to 70.6% and +1.2, spending most of the safety margin at once.
K12 is first: J11, K11, and N10 keep central contact forcing; Black remains about 92.8% and +6.9.
M10 also enters the center but scores only about 88.9% and +3.7, showing that similar direction is not equal order.
S7 exchanges S8 before returning to K12; 1,464 visits support the edge-first order at about 92.7%.
Respect begins by refusing a prettier false legend
Finishing the game is a real wartime event, not proof that Go stands above life. The board shows only the small order the players could still control.
Catastrophe needs no AI score; a professional choice can be analyzed. Holding both boundaries keeps the Atomic Bomb Game from becoming a sensational headline.