The Kanto Plain near Tokyo was the target of Operation Coronet, the second phase of Operation Downfall.
Coronet was planned as the follow-up to Operation Olympic, which would have invaded southern Kyushu. Allied planners expected Coronet to begin in spring 1946 after Olympic secured airfields and other positions. The objective was the Kanto Plain on Honshu, Japan’s largest island, including the area around Tokyo.
The Kanto Plain was strategically important because it contained Japan’s political center, major population concentrations, transportation links, and industrial resources. Capturing it would have placed immense pressure on the Japanese government and military command.
Coronet was never launched. Japan accepted surrender terms in August 1945, so the invasion plan was canceled before either phase began. Some accounts use “Operation Downfall” for the entire invasion plan and “Olympic” and “Coronet” for its two component operations; they were not separate completed campaigns.