We could trace the beginning of modern Japan to 1868, which is called the "Meiji Restoration." Before this date, Japan was <em>de facto</em> governed by local leaders called shogun. However, after this date, the emperor was restored to power. This began the period of the Empire of Japan.
During these years, the Meiji government was very interested in transforming the nation into a developed, Western state. It also wanted Japan to become an imperialist power. Japan became modernized, engaged internationally in trade relations, and developed its army. In order to fulfill its dream of expansion, it battled against many countries, such as Taiwan, China and Russia. These imperialist interests would ultimately lead them to join World War II.