Kyushu was the planned target of Operation Olympic before Japan surrendered.
Operation Olympic was designed to capture the southern portion of Kyushu, the southernmost of Japan’s four main islands. Allied planners intended to seize airfields and establish a base for supporting Operation Coronet, the proposed later invasion of the Kanto Plain near Tokyo on Honshu.
The planned landing was scheduled for November 1, 1945, but Japan’s surrender in August canceled the operation. Kyushu was chosen because its southern regions offered locations suitable for large amphibious landings and air bases, although Japanese defenses were being rapidly strengthened.
Honshu was the target of Coronet, not Olympic. Shikoku and Hokkaido were considered in various planning discussions or deception plans, but neither was the principal target of Olympic. The operation therefore belongs to the history of a planned invasion that never took place.