Inside, they barricaded the office and tied the commandant to his chair. Mishima wore a white hachimaki headband with a red hinomaru circle in the center bearing the kanji for "To be reborn seven times to serve the country" (七生報國, Shichishō hōkoku), which was a reference to the last words of Kusunoki Masasue, the younger brother of the 14th century imperial loyalist samurai Kusunoki Masashige (楠木正成), as the two brothers died fighting to defend the Emperor.[177] With a prepared manifesto and a banner listing their demands, Mishima stepped out onto the balcony to address the soldiers gathered below. His speech was intended to inspire a coup d'état to restore the power of the emperor. He succeeded only in irritating the soldiers, and was heckled, with jeers and the noise of helicopters drowning out some parts of his speech.

After he finished reading his prepared speech in a few minutes' time, Mishima cried out "Long live the Emperor!" (天皇陛下万歳, Tenno-heika banzai) three times. He then retreated into the commandant's office and apologized to the commandant, saying,

"We did it to return the JSDF to the Emperor. I had no choice but to do this."

Mishima then committed seppuku, a form of ritual suicide by disembowelment associated with the samurai. Morita had been assigned to serve as Mishima's second (kaishakunin), cutting off his head with a sword at the end of the ritual to spare him unnecessary pain. However, Morita proved unable to complete his task, and after three failed attempts to sever Mishima's head, Koga had to step in and complete the task.