In the 1920s and 1930s, Japan became much more xenophobic and turned inwards on itself, which led to it being very susceptible to fascist and nationalist ideologies. This, in turn, led to its contributions in World War 2 as one of the main Axis countries trying to spread fascism.
An economic depression spread throughout the country, which impacted their view of foreign trade and economies negatively. As they relied on foreign trade, they became frustrated that the economic climate outside the country was causing stagnation inside.
In addition, the Sino-Japanese war and the Russo-Japanese war further distanced and frustrated them with exterior political powers. They grew resentful of other, larger countries, and thought that they would benefit from expanding their own empire and being able to control more nations to aid their production and economic growth, as well as not having to deal with competing nations and getting into violent military disputes.