What was the planned March 1946 invasion of Honshu in Operation Downfall called?

Operation Coronet was the planned March 1946 invasion of Honshu in Operation Downfall.

Coronet was intended to follow Operation Olympic, the planned invasion of southern Kyushu. Its objective was the Kanto Plain near Tokyo, on Japan’s largest and most populous main island, Honshu.

The tentative Y-Day for Coronet was March 1, 1946. Planners expected the operation to be larger than Olympic because it would attack the area around Tokyo and require a major concentration of Allied ground forces.

Japan’s surrender in August 1945 made Coronet unnecessary. It is often confused with Operation Olympic, but the two names referred to separate phases: Olympic for Kyushu and Coronet for the Tokyo region of Honshu.