The emperor of Japan during World War II was Emperor Hirohito. He ascended to the throne in 1926 and reigned throughout Japan's militaristic expansion leading up to and during the war. Hirohito's role is complex; while he was regarded as a divine figurehead and a symbol of the Japanese state, the extent of his authority and involvement in military decisions has been debated by historians. His reign saw Japan's aggressive policies, including the invasion of China and the attack on Pearl Harbor in 1941. Following Japan's defeat in 1945, Hirohito's role shifted to becoming a constitutional monarch in the post-war era.