Which phase of the planned Operation Downfall invasion targeted Japan’s island of Kyūshū?

Operation Olympic was the phase of planned Operation Downfall that targeted Japan’s island of Kyūshū.

Olympic was designed as the first stage of a massive Allied invasion of the Japanese home islands. The plan called for U.S. Sixth Army forces to land in southern Kyūshū and establish positions for later operations. Its proposed launch date was November 1, 1945, although planning continued to change as military conditions developed.

The second stage was Operation Coronet, planned for March 1, 1946. Coronet would have attacked the Kantō Plain near Tokyo on Honshū. Together, Olympic and Coronet formed Operation Downfall, the overall invasion plan that was never carried out because Japan surrendered in August 1945.

Operation Olympic is sometimes confused with Operation Iceberg, the codename for the 1945 invasion of Okinawa. It was also separate from Japan’s own defensive plan, Operation Ketsu-Go. The surrender therefore prevented what Allied planners expected to be an extremely costly campaign on the Japanese mainland.