What was the Showa period like before the end of World War ll?

It is difficult to explain in brief the Showa period because of the fundamental difference between the pre-World War II period before Japan's defeat in 1945 and the postwar period which lasted until 1989.
After the Russo-Japanese War, Japan continued its policy of extending power in Manchuria, and the Kwantung army stationed on the continent furthered its occupation of Manchuria, and in 1932 issued the "Declaration of the Founding of Manchukuo."
In protest, the League of Nations sent an investigative commission to Manchuria, while Japan withdrew from the League.
In 1937, propelled by the Marco Polo Bridge Incident when Japanese forces on night training clashed with Chinese troops, Japan entered into a war with China, and soon it intervened in all of Southeast Asia.
Japan's attack on Pearl Harbor on December 8th 1941 signaled its thrust into full-scale war with the United States and other countries.
In the end, Japan was defeated in August 1945.