In Operation Downfall, what was the planned Allied invasion of southern Kyūshū called?

The planned Allied invasion of southern Kyūshū was called Operation Olympic.

Olympic was the first stage of Operation Downfall, the proposed invasion of Japan’s home islands. The plan called for landings in southern Kyūshū, Japan’s southernmost main island, to capture territory and airfields for a later advance.

The second stage, Operation Coronet, was planned for the Kantō Plain near Tokyo on Honshū. Downfall was therefore the overall invasion plan, while Olympic and Coronet were its two major components.

Japan’s surrender made the invasion unnecessary. The atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and Japan’s decision to accept the Allied terms ended the war before Olympic could begin.