What was the codename for the planned second stage of Operation Downfall near Tokyo?

Operation Coronet was the codename for the planned second stage of Operation Downfall near Tokyo. It was intended to invade the Kantō Plain on Japan’s main island, Honshū, in spring 1946.

The operation would have followed Operation Olympic, the planned November 1945 landing in southern Kyūshū. Captured airfields and territory from Olympic were expected to provide support for the advance toward the Kantō region. The area included Tokyo and was the political and industrial heart of Japan.

Coronet was never launched because Japan surrendered in August 1945. Its cancellation reflected the dramatic change brought by Japan’s acceptance of the Allied terms, rather than a successful execution of the invasion plan.

The Japanese defensive plan was called Operation Ketsugō, not Coronet. Ketsugō was Japan’s preparation for resisting an invasion of the home islands, while Coronet was the Allied plan for attacking them. Keeping the two codenames separate avoids a common historical confusion.