Operation Coronet was the planned Operation Downfall phase that would have invaded Japan’s main island of Honshu in spring 1946.
Coronet was scheduled to begin on March 1, 1946, with landings on the Kantō Plain near Tokyo. The plan called for U.S. forces to attack from beaches including Kujūkuri Beach and areas around Sagami Bay, then advance toward the capital.
Operation Coronet was the second part of Operation Downfall. The first part, Operation Olympic, was scheduled for November 1, 1945, and would have invaded southern Kyūshū. Japan’s surrender canceled both operations before either began.
Japanese planners anticipated an Allied invasion and prepared Operation Ketsugō as a defense plan. Operation Pastel, meanwhile, was a proposed Allied deception plan associated with Olympic, not the invasion of Honshu itself.