It is really hard to draw a line between the "democratic" and "miilitarist" or "fascist" era of Japan. There is no clear dividing line the way Hitler's coming to power was in Germany. As late as 1936 there was a moderately free election for the Diet, in which the openly radical right did quite poorly (400,000 votes and six seats), while a labor party (Shakai Taishuto or "social masses party") doubled its previous vote and won 18 seats. The party getting the most votes was the Minseito or Democratic party (4,456,200 votes and 205 seats)--whose governments of 1929-31 had probably been the high-water mark of Japanese liberalism. (During the 1936 campaign, the Minseito used as one of its slogans, "Which shall it be, parliamentary government or Fascism?") In the 1937 election, while the Minseito lost some ground, the Shakai Taishuto advanced (though by that time it was torn between social democracy and national socialism).
https://en.wikipedia.org/wiki/Japanese_general_election,_1937
OTOH, how democratic was the late 1920's? Here's a negative appraisal: "For example, the Seiyu Kai cabinet of April 1927 to July 1929 headed by General Tanaka Giichi was supposed to be a purely political party Cabinet. Yet in domestic policy it put severe pressure on the left-wing movements and further restricted freedom of speech, publication, and association by revising the Law for the Maintenance of Public Peace in the form of the Emergency Decree. Abroad it adopted the Tanaka 'positive diplomacy,' dispatching troops to China on the occasion of the Tsinan Incident. Until it collapsed after getting entangled in the assassination of Chang Tso-lin, its course of action almost appears to be that of a fascist government." Masao Maruyama, *Thought and Behavior in Modern Japanese Politics* (Oxford University Press paperback edition 1969), p. 81. In this perspective, the relative liberalism of the Minseito governments of 1929-31 was the aberration, and militarism the general rule.