What was the planned second stage of the Allied invasion of Japan called?

Operation Coronet was the planned second stage of the Allied invasion of Japan.

The operation was intended to follow Operation Olympic, which would have attacked southern Kyushu. Coronet was planned for March 1946 and would have targeted the Kanto Plain on Honshu, the main Japanese island containing Tokyo and other major population and industrial centers.

Operation Olympic and Operation Coronet together made up Operation Downfall, the overall Allied plan for invading Japan’s home islands. Military planners expected the campaign to be extremely costly because Japan was preparing a large-scale defense of its territory.

Coronet was never launched. Japan accepted the Allied surrender terms in August 1945, and the formal surrender ceremony followed on September 2. Operation Coronet is therefore a historical invasion plan, not the name of an operation that actually took place.