[Animats]

How Japan made the decision to surrender is well covered in the book "Japan's Longest Day", originally published in 1973. Many of the major players were interviewed. There's a reasonably accurate movie version worth watching, if you're interested in this.

It's a very strange story of decision-making under extreme pressure. No one was in charge. The Navy was barely talking to the Army. The civilian government had been sidelined from control of military matters years before. The Emperor was supposed to be a figurehead. And, as pointed out above, there was an attempted coup to stop the surrender.