On what date did the Allied occupation of Japan begin, before the formal surrender ceremony?

The Allied occupation of Japan began on August 28, 1945, before the formal surrender ceremony.

On that date, about 150 American personnel flew into Atsugi in Kanagawa Prefecture. They were among the first Allied personnel to arrive under the occupation plan, which was directed by General Douglas MacArthur as Supreme Commander for the Allied Powers.

The USS Missouri and other Allied vessels followed, and the 4th Marine Regiment landed on the southern coast of Kanagawa. MacArthur arrived in Tokyo on August 30, two days before the signing ceremony in Tokyo Bay.

The occupation continued for almost seven years. The Treaty of San Francisco was signed in 1951 and came into force on April 28, 1952, formally ending the Allied occupation and restoring Japan's sovereignty, with some territories handled separately. The occupation reshaped Japan's political institutions, military policy, and constitution.