What was the planned second phase of Operation Downfall, aimed at Honshu, called?

The planned second phase of Operation Downfall, aimed at Honshu, was called Operation Coronet.

Coronet was designed to follow Operation Olympic after Allied forces secured southern Kyushu. Its objective was the Kantō Plain on Honshu, the main island of Japan and the location of Tokyo. The proposed attack date was March 1, 1946, although the plan remained subject to military developments and operational decisions.

The Kantō Plain offered room for large-scale land operations and contained Japan’s political center. Capturing the area would have placed Tokyo and surrounding communications networks under direct Allied threat. American planners expected the Japanese defense to be extensive, drawing on regular troops and civilian mobilization.

Coronet was never executed. Japan’s surrender in August 1945 removed the need for Downfall, meaning that both planned invasion phases remained historical contingencies. The names are easy to reverse: Olympic referred to Kyushu, while Coronet referred to the later Honshu operation.