What was the planned second phase of Operation Downfall against the Tokyo region called?

The planned second phase of Operation Downfall against the Tokyo region was called Operation Coronet.

Coronet was intended to follow Operation Olympic, the proposed invasion of southern Kyushu. Its target was the Kantō Plain on Honshu, the main Japanese island, with the objective of capturing the area around Tokyo. Planning placed the operation in spring 1946, after Allied forces had established bases and staging areas during Olympic.

Operation Downfall was therefore an umbrella name, not the name of a single landing. Olympic and Coronet were its two component operations. This distinction matters because many summaries use Downfall when discussing the entire proposed invasion, while Coronet refers specifically to the later Honshu phase.

Japan’s surrender canceled both operations. Japanese leaders were preparing their own defense plan, Operation Ketsugō, which envisioned mass mobilization and determined resistance against an invasion. The resulting historical debate often concerns how many casualties Coronet and Olympic might have caused, but no final battle estimates can be verified as actual losses because the operations never began.