The was a period of Japanese history corresponding to the reign of Emperor Shōwa (Hirohito) from December 25, 1926, until his death on January 7, 1989.Nussbaum, Louis-Frédéric. (2005). "Shōwa". . It was preceded by the Taishō era and succeeded by the Heisei era.

In the late 1920s, Japan had begun moving into political totalitarianism, ultranationalism and statism, culminating in Japan's invasion of China in 1937, part of a global period of social upheavals and conflicts such as the Great Depression and the Pacific War.

Defeat in the Second World War brought about radical change in Japan. For the first and only time in its history, Japan was occupied by foreign powers, an American-led occupation which lasted for six years and eight months. Allied occupation brought forth sweeping democratic reforms. It led to the formal end of the emperor's status as a demigod and the transformation of Japan from a form of mixed constitutional and absolute monarchy to a constitutional monarchy and parliamentary system with a liberal democracy. In 1952, with the Treaty of San Francisco, Japan became a sovereign state again. The postwar Shōwa period was characterized by the Japanese economic miracle.

The Shōwa era was longer than the reign of any previous Japanese emperor. Emperor Shōwa was both the longest-living and longest-reigning historical Japanese emperor as well as the longest-reigning monarch in the world at the time. On 7 January 1989, Crown Prince Akihito succeeded to the Chrysanthemum Throne upon the death of his father, Emperor Shōwa, which marked the start of the Heisei era. Emperor Hirohito was served by a total of 33 prime ministers, beginning with Wakatsuki Reijirō and ending with Noboru Takeshita.

Etymology The two kanji characters in Shōwa () were from a passage of the Chinese Book of Documents: (Translated: "[T]he people (of his domain), ... all became brightly intelligent. (Finally), he united and harmonized the myriad states.") From this same quotation, Japan also adopted the era name Meiwa () during the Edo period in the late-18th century. There were two other candidates at the time – Dōwa () and Genka ().

The term could be roughly understood as meaning "enlightened peace" or in some interpretations "radiant Japan".

In his enthronement address which was read to the people, the Emperor referenced this era name:

I have visited the battlefields of the Great War in France. In the presence of such devastation, I understand the blessing of peace and the necessity of concord among nations.Durschmied, Erik (2002). Blood of Revolution: From the Reign of Terror to the Rise of Khomeini, p. 254.

Decline of "Taishō Democracy"

The election of Katō Takaaki as the Prime Minister of Japan continued democratic reforms that had been advocated by influential individuals on the left. This culminated in the passage of universal male suffrage in May 1925. The General Election Law gave all male subjects over the age of 25 the right to vote, provided they had lived in their electoral districts for at least one year and were not homeless. The electorate thereby nearly quadrupled in size, from 3.3 million to 12.5 million.Hane, Mikiso, Modern Japan: A Historical Survey (Oxford: Westview Press, 1992) 234.

This increase in the electorate coincided with the passage of Peace Preservation Law of 1925 along with other anti-left-wing legislation.Sharon Minichiello, Retreat from Reform: Patterns of Political Behavior in Interwar Japan (University of Hawaii Press, 1984).Germaine A. Hoston, "The state, modernity, and the fate of liberalism in prewar Japan". Journal of Asian Studies 51.2 (1992): 287-316. The Peace Preservation Act curtailed activism on the left — which was not extensive — and the screws were steadily tightened. It outlawed groups that sought to alter the system of government or to abolish private ownership.

The small leftist movements that had been galvanized by the Russian Revolution were subsequently crushed and scattered. This was in part due to the Peace Preservation Act, but also due to the general fragmentation of the left. Conservatives forced the passage of the Peace Preservation Law because the party leaders and politicians of the Taishō era had felt that, after World War I, the state was in danger from revolutionary movements. Hence, a proposal for socialist reforms, was seen as an attack on the very existence of the state. The meaning of the law was gradually stretched to academic spheres. After the passage of the Peace Preservation Law and related legislation, kokutai emerged as the symbol of the state. Kokutai was seen as the bulwark against communist and socialist movements in Japan. With the challenge of the Great Depression on the horizon, this would be the death knell for parliamentary democracy in Japan.Richard H. Mitchell, "Japan's Peace Preservation Law of 1925: Its origins and significance", Monumenta Nipponica (1973): 317-345. .

Washington Conference to Mukden Incident

After World War I, the Western Powers, influenced by Wilsonian ideology, attempted an effort at general disarmament. At the Washington Naval Conference of 1921–1922, the Great Powers met to set limits on naval armament. The Five Power Naval Limitation Agreement worked out in Washington limited competition in battleships and aircraft carriers to a ratio of 5:5:3 (in terms of tonnage) for the United Kingdom, the United States, and Japan respectively. Japanese ultra-nationalists viewed this as an attempt by Western powers to curb Japanese expansionism in an area of the globe over which they had no interest. However, those in power in Japan readily agreed to the disarmament, realizing that the global taste for war had been soured after the First World War and knowing that, the ratio was sufficient to maintain hegemony in the Pacific.

In 1924, however, friendly U.S.–Japanese relations were torpedoed by the Immigration Act of 1924. The act closed off Japanese immigration to the United States and dropped Japanese immigrants to the level of other Asians (who were already excluded). The overwhelming reaction in Japan, both at the highest levels and in mass rallies that reflected angry public opinion, was hostile and sustained. Commentators suggested the opening guns of a race war and called for a new buildup of the Imperial Japanese Armed Forces.Izumi Hirobe, Japanese Pride, American Prejudice: Modifying the Exclusion Clause of the 1924 Immigration Act (2001) ch 4

The Shōwa financial crisis was a financial panic in 1927, during the first year of the reign of Emperor Hirohito. It was a precursor of the Great Depression. It brought down the government of Prime Minister Wakatsuki Reijirō and led to the domination of the zaibatsu over the Japanese banking industry.

From 1928 to 1932, a domestic crisis could no longer be avoided. As the left was vigorously put down by the state, the economic collapse brought new hardship to the people of Japan. Silk and rice prices plummeted and exports decreased 50%. Unemployment in both the cities and the countryside skyrocketed and social agitation came to a head. Most of the military recruits were from the countryside and they brought their anger against the government into the military.

Meanwhile, the London Naval Treaty was ratified in 1930. Its purpose was to extend the Washington Treaty System. The Japanese government had desired to raise their ratio to 10:10:7, but this proposal was swiftly countered by the United States. Thanks to back-room dealing and other intrigues, though, Japan walked away with a 5:4 advantage in heavy cruisers,Tohmatsu, Haruo; Willmott, H. P. A Gathering Darkness: The Coming of War to the Far East and the Pacific, 1921–1942 (Lanham, Maryland: SR Books, 2004), pp. 26–27. but this small gesture would not satisfy the populace of Japan, which was gradually falling under the spell of the various ultra-nationalist groups spawning throughout the country. As a result of his failings regarding the London Naval Treaty, Prime Minister Hamaguchi Osachi was shot on November 14, 1930, by an ultranationalist and died in 1931.

By this time, the civilian government had lost control of the populace. A New York Times correspondent called Japan a country ruled by "government by assassination".Pyle, Kenneth, The Rise of Modern Japan, p. 189. The army, moving independently of the proper government of Japan, took the opportunity to invade Manchuria in the summer of 1931.

Since the Russo-Japanese War of 1905, Japan had maintained a military presence in Manchuria. On September 18, 1931, the Mukden Incident occurred. There was a small explosion on the tracks of a Japanese railway, north of Mukden. Japan invaded Manchuria in the aftermath. The Imperial Japanese Army mobilized the Kwantung Army and attacked Chinese troops. The Minseito government, headed by Hamaguchi's successor Wakatsuki Reijirō, was unable to curb the army's offensive. The Kwantung Army conquered all of Manchuria and set up the puppet state of Manchukuo on March 1, 1932. The last Emperor of China, Puyi, was installed as the puppet ruler of Manchukuo. The Diet, now dominated by army officials, voted to withdraw from the League of Nations. The first seeds of the coming conflict had been sown.

Rise of nationalism

Prior to 1868, most Japanese more readily identified with their feudal domain rather than the idea of "Japan" as a whole. When the Tokugawa shogunate was overthrown, the leaders of the revolt, Satsuma and Chōshū, were ideologically opposed to the house of Tokugawa since the Battle of Sekigahara. The Meiji era changed all of that. With the introduction of mass education, conscription, industrialization, centralization, and successful foreign wars, Japanese nationalism began to foment as a powerful force in society. Mass education and conscription served as a means to indoctrinate the coming generation with "the idea of Japan" as a nation state instead of a series of daimyōs. In this way, loyalty to feudal domains was supplanted with loyalty to the central government. Industrialization and centralization gave the Japanese a strong sense that their country could once more rival and dominate Western powers technologically and socially. Moreover, successful foreign wars gave the populace a sense of martial pride and overconfidence in the strength of their country.

The rise of Japanese nationalism paralleled the growth of nationalism within the West. Certain conservatives such as Gondō Seikei and Asahi Heigo saw the rapid industrialization of Japan as something that had to be tempered. During the Meiji era, such nationalists railed against the unequal treaties, but in the years following the First World War, Western criticism of Japanese imperial ambitions and restrictions on Japanese immigration changed the focus of the nationalist movement in Japan.

Japanese nationalism was buoyed by a romantic concept of Bushidō and driven by a modern concern for rapid industrial development and strategic dominance in East Asia. It saw the Triple Intervention of 1895 as a threat to Japanese success in East Asia and warned that the "ABCD Powers" (America, Britain, China, and the Dutch), were threatening the Empire of Japan. One solution was war.Michael Edward Brown, et al. Nationalism and Ethnic Conflict (2001) p. 50.Edwin P. Hoyt, Warlord: Tojo Against the World (1983) pp 43-54.Robert J.C. Butow, Tojo and the Coming of the War (1961)