What was the overall Allied invasion plan for the Japanese home islands called?

The overall Allied invasion plan for the Japanese home islands was called Operation Downfall.

Downfall was divided into two proposed operations. Operation Olympic was the planned invasion of southern Kyushu, scheduled for November 1945. Operation Coronet was the proposed later assault on Honshu near the Kanto Plain, scheduled for March 1946.

The plan reflected Allied preparations for a possible continuation of the Pacific War after the defeat of Germany. It included large-scale naval, air, and ground-force commitments, as well as plans for occupation and logistics. Japanese authorities also prepared defensive measures for an expected invasion of the home islands.

Operation Downfall was never executed because Japan accepted the Potsdam Declaration in August 1945. The atomic bombings, the Soviet attack on Japanese forces, the naval blockade, and internal Japanese decision-making all form part of historical debates about why surrender occurred when it did.