I love this question, The pre-war period is my favorite part of Japanese history, but Im hundreds of miles away from my computer and reference materials so I cant write a good response. Don`t be surprised if there is an edit in two or three weeks time with a lot more info.

I`ll start by linking to this monster post I wrote on Japanese militarism which you may find useful.

Pre-War Japanese society is fascinating. In the interests of brevity i`ll split prewar Japan into two parts, 1920 (The start of the heyday of the Taisho Democracy) to 1933 (assassination of Inukai Tsuyoshi) and 1933 to 1941. But things are a little bit more complicated than that and I encourage further research as always.

By 1920 Japan was one of the economic powerhouses of the world. While the Europeans had sacrificed milllions of men and the production of their entire nations in the First World War, Japan had focused on its economy and came through mostly unscathed (For the first time, Japan changed from a borrowing nation to a lending nation). Japan had also had its share of the spoils of war, with new possessions in China and the Pacific as well as a seat at the League of Nations Security Council.

Japan was also an increasingly liberal and progressive country. The new Emperor since 1912, Emperor Taisho, was (possibly) feeble-minded and was both pro-west and pro-liberlism as far as we can gauge from his few public appearances. Japan`s prime minister, Hara Takashi, was a party politician as opposed to the Oligarchs that had dominated Japanese politics before the war.

Japanese Society during Taisho is nicknamed Ero, Guru, Nansensu (Erotic, Grosteque and Nonscensical) if that gives you an idea of what it was like. People dressed in European style clothes and talked politics, philosophy and foreign poilicy in public. Young people who talked politics were nicknamed Marx Girls and Marx Boys, reflecting their likely political leanings. European Style Cafes and Bars covered the streets. Art-Deco Theaters, Opera Houses and flashy hotels were opened everywehere to service Japans growing middle and upper classes, which included an increasing number of Journalists which was a rising profession. Universities and Higher education were also becoming more common (the first womens university in Japan opened in 1918) and liberal and communist ideas filled their halls. Indeed, liberalism permeated every part of society, even the army. One army commander complained soldiers had become rebellious due to the rise in general knowledge and social education.`

But a sickening stench covered this liberalism, the stench of ultra-nationalism that would later plunge Japan into WW2. Leading leftists in Japan supported Japan`s imperial adventures in Korea and China and 15 years earlier, when riots had wracked Japan at the end of the Russo- Japanese War because people felt Japan had not punished Russia sufficiently, some of the leading rioters had been members of leftist organizations.

In 1923 the vote was extended to all men over 25 who could prove a steady income. However, the same year the Peace Preservation law was also passed, which allowed the government to arrest anyone who was opposed to the Kokutai or national polity. What this meant in reality was members of far leftisist organizations were driven out of government and arrested. This back and forth push between Democracy and Authoritarianism characterized the government of the Taisho Era.

One interesting Characteristic of later Taisho Japan is that the cool intellectual thing became supporting Fascism, Imperialism and Authoritarianism. We imagine Paris in the 20s as a place where the world greatest liberals talked about democracy. Late 1920s Tokyo was similar, except Japans greatest intellectuals gathered to talk about utter devotion to the emperor and other authoritarian concepts. People like Kita Ikki and Tamakura Kotaro pressed ideas of Japanese Racial superiority and the neccessirty of an Authoritarian government. In the case of Tamakura Kotaro, he had started out as one of Japan`s liberal Marx Boys, but somewhere became disillusioned and became graudually more right wing and extreme.

With this in mind, its easy to see how the seemingly strong Taisho Democracy was balanced on a knifes edge and collapsed so easily.

EDIT: Japanese Phone Keyboard:s don`t like me, excuse the bizarre formatting and any typos

Er this is false. There was no dictator in Japan in modern times. It was wartime US propaganda that tried to link Japan with Nazi Germany and Fascist Italy and so made Tojo Hideki into an equivalent of real dictators, Adolf Hitler and Benito Mussolini.

Tojo Hideki was a Prime Minister who got to power through normal channels in prewar Japan. And lost power in 1944 when Saipan fell (replaced by Koiso Kuniaki). A dictator usually is not forced out of office peacefully.

Basically prewar Japan had a number of competing power centers. One was of course the military (the army and the navy). Another was the bureaucracy (the home ministry, the treasury ministry, the foreign ministry, etc). Another was the elected politicians (the Seiyukai and the Minseito were the 2 major parties in the 1930s). Finally there was the zaibatsu or the Money Cliques (the 4 major conglomerates were Mitsui, Mitsubishi, Sumitomo, and Yasuda).

One way to think of what happened is that the Great Depression (and the earlier Show financial crisis of 1927) weakened the influences of the zaibatsu (who were seen to be in charge of the economy) and the elected politicians (who were seen to be incompetent in fixing the broken economy).

This left the military and the bureaucracy as the only 2 groups in charge. But with war starting in Manchuria (in 1931), the military steadily gained the upper hand.

After two coup d'etat attempts by right wing fascists (1932.5.15 and 1936.2.26), the military decided to take the center stage. And so from 1932 to 1945, most of the Prime Ministers of Japan were from the army or the navy.

If you cut out this part of Japanese history, you can say that Japan was militarist during the 1930s and 1940s. But again there was no dictator. These Prime Ministers were selected through the legal channel established in the 1889 Constitution with no one having dictatorial powers.

Now to complicate matters, you can also say that Japan was fascist in the 1930s and the 1940s. This is because the successive governments of Japan after the 1930s implemented fascist policies.

The National Total Mobilization Law of 1938, the abolition of all political parties except the Taisei Yokusankai in 1940, and the proclamation of the Greater East Asian Co-Prosperity Sphere in 1940, are all fascist policies. The first for the economy, the second for domestic politics, and the third for foreign policy. All 3 of the above were ironically done under a civilian Prime Minister, Konoe Fumimaro (an aristocrat and not a military man).

So what was prewar Japan? Trying to forcibly apply European historical precedents to Japan doesn't really work. I personally don't think it was militarist.

However, after 1938 especially, I think you can say that Japan became a fascist country. Not a fascism from below, with a mass political party and a dictator leading it like Germany, Italy, or Spain, but rather a fascism from above by a collusion of military, bureaucratic, political, and capitalist leaders to protect their interests.

For this period I suggest reading some books that covers the topic widely. Then if you are interested to dig in further there are more books!

Andrew Gordon, A Modern History of Japan and Marius Jansen, The Making of Modern Japan are both very good starting points.

Ienaga Saburo, The Pacific War (to get a sense of the atmosphere at the time)

Richard Smethurst, A Social Basis for Prewar Japanese Militarism: The Army and the Rural Community (this is an old book, so you probably have to get it from a library but it shows how the military had a strong influence in Japanese life before the war)

Chalmers Johnson, MITI and the Japanese Miracle (see the first 5 chapters to see how the bureaucracy tried to gain the upper hand)

Michael Barnhart, Japan Prepares for Total War: The Search for Economic Security, 1919-1941 (covers the economically driven aspects of prewar Japanese concerns, namely resources and markets)

And then there are biographies on Konoe Fumimaro to see how the political class really screwed up (by first failing to address the economy and by second by falling in love with fascism instead of democracy). A translation from the Japanese is Oka Yoshitake, Konoe Fumimaro. I haven't read this book, but Kazuo Yagami, Konoe Fumimaro and the Failure of Peace in Japan, 1937-1941 is a relatively new book (2006).

Personally I think the assassination of Takahashi Korekiyo (a civilian Minister of Treasury and also Prime Minister) sealed the fate of Japanese politicians. He was really the only guy who knew how to fix the economy before the war. Richard Smethurst, From Foot Soldier to Finance Minister: Takahashi Korekiyo, Japan's Keynes