The Japanese leader during World War II was Emperor Hirohito, who reigned from 1926 to 1989. While he was the ceremonial head of state, the real power during the war primarily resided with military leaders, including Prime Ministers like Hideki Tojo. Under Hirohito's reign, Japan pursued aggressive expansionist policies, resulting in invasions of various countries in East Asia and the Pacific, culminating in the attack on Pearl Harbor in 1941. After Japan’s defeat in 1945, Hirohito was retained as emperor, but his role transitioned to a more symbolic one, contributing to Japan's post-war reconstruction and pacifism.