What was the second phase of the planned Allied invasion of Japan, aimed at the Kanto Plain?

Operation Coronet was the second phase of the planned Allied invasion of Japan, aimed at the Kanto Plain.

Coronet was intended to follow Operation Olympic in spring 1946. Its objective was the Kanto Plain on Honshu, the main Japanese island, including the area around Tokyo. Capturing this region would have placed Allied forces at the center of Japan's government and population.

The operation was part of Operation Downfall, the overall invasion plan. Olympic would first secure southern Kyushu and provide bases for air support. Coronet would then use those bases and additional forces for the assault on Honshu.

Japan's surrender made Coronet unnecessary. The plan is sometimes mistakenly called the invasion itself, but Downfall was the umbrella operation, Olympic was the Kyushu phase, and Coronet was the later Honshu phase. Coronet's proposed scale was enormous and would have required forces from several Allied countries.