Smallest PoD necessary for Japanese islands campaign?

[joseph34]

What is the smallest change you can make to events in August 1945 that will snowball into the infamous Operation Downfall? Preferably a POD after the Nagasaki bombing.

 

[oboro]

This answer doesn’t fit any of your requirements, but I’ve wondered what would have happened if the Allies were ready to invade Japan before the A-bombs were ready, say by having the Pacific campaign go 6 months or a year ahead of schedule

 

[nbcman]

Successful Kyujo Incident / coup:

Kyūjō incident - Wikipedia

en.m.wikipedia.org

The IJA takes over and continues resistance after the A bombings

 

[SunKing105]

The emperor doesn't manage to send out his servant with the surrender recordings in time, allowing the coup plotters find it and destroy it, leading to a successful Kyujo coup. It's scary how close we came to this reality.

 

[CalBear]

Successful Kyujo Incident / coup:

Kyūjō incident - Wikipedia

en.m.wikipedia.org

The IJA takes over and continues resistance after the A bombings

The emperor doesn't manage to send out his servant with the surrender recordings in time, allowing the coup plotters find it and destroy it, leading to a successful Kyujo coup. It's scary how close we came to this reality.

And completely in alignment with so many of Japan's history altering actions since it would be the result of a couple field officers gone rogue.