What was the Allied plan to invade Japan’s home islands called before Japan surrendered?

The Allied plan to invade Japan’s home islands before Japan surrendered was called Operation Downfall.

Downfall was the proposed United States and British Empire invasion plan for mainland Japan. It was divided into two major stages: Operation Olympic, aimed at southern Kyushu in November 1945, and Operation Coronet, planned for the Kanto Plain near Tokyo in spring 1946.

Japan’s surrender made the invasion unnecessary. The decision followed the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the rapid collapse of Japan’s strategic position. Downfall was therefore canceled before its planned operations began.

Operation Olympic and Operation Coronet are sometimes mistakenly offered as alternatives to Downfall, but they were components of the larger plan. Japan’s own defensive response was called Operation Ketsugō.