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

The planned Allied invasion of Honshu in Operation Downfall was called Operation Coronet.

Coronet was intended as the second stage of the proposed invasion of Japan. Its objective was the Kanto Plain on Honshu, near Tokyo, after Operation Olympic had established bases in southern Kyushu. Planners tentatively scheduled Coronet for March 1, 1946, although the exact plans evolved during 1945.

The operation was expected to be larger than Olympic and would have involved landings around the Kanto region. American forces were to approach from areas including Sagami Bay and the Boso Peninsula, then advance toward Tokyo. British Commonwealth forces were also considered for later reinforcement operations.

Coronet never took place. Japan’s surrender in August 1945 followed the atomic bombings of Hiroshima and Nagasaki and the Soviet entry into the war against Japan. Operation Downfall, the umbrella name for Olympic and Coronet, was therefore canceled. Operation Pastel was a separate deception plan associated with Olympic, not the name of the Honshu invasion itself.