The attempted coup that sought to stop Hirohito’s surrender broadcast was the Kyūjō incident.
The Kyūjō incident took place in Tokyo during the night of 14–15 August 1945, just before the emperor’s recorded address was scheduled to air. Major Kenji Hatanaka and other military officers tried to seize the Imperial Palace, place Hirohito under house arrest, and locate or destroy the recording that announced acceptance of the Potsdam Declaration.
The plotters struggled to secure support from senior commanders. They killed Lieutenant General Takeshi Mori of the Imperial Guards Division and attempted to use a forged order to occupy the palace, but the broader army leadership did not authorize the operation. The coup collapsed after the Eastern District Army refused to support it and palace officials protected the recording.
The incident is sometimes called the Imperial Palace incident. It was not a successful change of government, and it did not prevent the broadcast. Several plot leaders later committed suicide, while the emperor’s address was transmitted at noon on 15 August, making the surrender public to Japan.