The failed Japanese coup attempt just before the 1945 surrender broadcast was the Kyūjō incident.
The Kyūjō incident occurred during the night of August 14–15, 1945, as army officers tried to prevent Japan’s surrender from being announced. The plotters sought to place Emperor Hirohito under house arrest and destroy the recording of his surrender message.
Major Kenji Hatanaka was among the coup’s leading figures. Rebels occupied parts of the Imperial Palace and killed Lieutenant General Takeshi Mori, but they failed to secure support from senior army commanders. The Eastern District Army and other authorities refused to back the takeover.
The coup collapsed before the scheduled radio broadcast. The surrender recording survived and was delivered to NHK, allowing the emperor’s message to be transmitted at noon on August 15. Several coup leaders later committed suicide. The incident is also called the Kyūjō Incident, using a romanization of the Japanese word for the Imperial Palace.