Here are a number of documents related to the planning.
There were two invasions of Japan planned as part of Operation Downfall.
They were Operation Olympic and Operation Coronet.
The last section-the bombing of Akita was the last big raid on Japan and happened after Hiroshima and Nagasaki.
Little is known about this raid.
The fire bombing of Tokyo and the raid on Akita were more destructive than either atomic bomb, but they are largely ignored by history.
General Doolittle commented that if we had lost the war, he would have been executed as a war criminal because of the fire bombings.