In the 20th century, Japan was emerging as a formidable military power, which also led to a rise in its national pride. It invaded and annexed various parts of Asia and the Pacific Islands, including Taiwan and Korea, all in the name of the Japanese emperors who were revered and worshiped as deities. Even before World War II, tensions existed between Japan and the US as well, especially after the US passed the Immigration Act of 1924 (the Johnson-Reed Act), forbidding further immigration from Asia.

The Pacific Theater of World War II was also hard-won, with many casualties on both sides. Japan was strafed with firebombs, and the battles of Okinawa and Iwo Jima were hard-fought and bloody, with the US troops emerging victorious. After the devastation of the atomic bombs on Hiroshima and Nagasaki in 1945, Japan surrendered, and the Allied forces dissolved the Empire of Japan. The Japanese army was demilitarized, and the emperor’s power was dissolved. Allied forces occupied Japan under General Douglas MacArthur; these consisted of primarily US military forces. Many Japanese government and military officials were tried for war crimes and executed; the Japanese Emperor remained on as a figurehead, though he had no real power.