when did it become a democracy?
After 1889.
Empire of Japan
Imperial Japan was founded, "de jure", after the 1889 signing of Constitution of the Empire of Japan.
when was the japanese battleship mutsu built? At the end of World War I. which navy did it serve? Imperial Japanese Navy. when was the navy created? In 1868. are they still active? No it was dissolved after Japan's surrender in World War II. was the navy serving an empire? Yes, the Empire of Japan. was there any particular type of democracy in the empire? It is a constitutional monarchy.
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Empire of Japan [SEP] Political reform
... In consideration of the progressive tendency of the course of human affairs and in parallel with the advance of civilization, We deem it expedient, in order to give clearness and distinctness to the instructions bequeathed by the Imperial Founder of Our House and by Our other Imperial Ancestors, to establish fundamental laws. ... Imperial Japan was founded, "de jure", after the 1889 signing of Constitution of the Empire of Japan. The constitution formalized much of the Empire's political structure and gave many responsibilities and powers to the Emperor.