What was the planned 1946 Allied invasion of the Kantō Plain called?

The planned 1946 Allied invasion of the Kantō Plain was called Operation Coronet.

Operation Coronet was the second phase of Operation Downfall, the proposed Allied invasion of Japan’s home islands. It was scheduled for spring 1946 and aimed at the Kantō Plain, the region surrounding Tokyo on Honshu.

The first phase, Operation Olympic, was planned for November 1945 and would have attacked southern Kyushu. Airfields captured during Olympic were intended to support Coronet. Japan’s surrender in August 1945 canceled both operations before either invasion took place.

Operation Coronet is often confused with Operation Olympic because both belonged to Operation Downfall. Downfall was the overall invasion plan, Olympic targeted Kyushu, and Coronet targeted the Tokyo region. Japanese planners prepared their own defensive strategy, Operation Ketsugō, anticipating that an Allied invasion might occur.