You have to acknowledge it and bring awareness to it. Treat women the same way men are. If you see sexism try and stop it
The correct answer is - oil.
The Japanese Empire, under the rule of Emperor Hirohito, in order to manage to continue with the expansion and gain new territories, needed much more oil than what its supplies where.
The need for oil meant that Japan will attack the places in the region where there are solid amounts of oil reserves, and they did. They attacked and conquered parts of Southeast Asia, and got hold onto the large oil reserves that they desperately needed for their military machinery.
There was very low economic growth during this time, along with an unsettle financial system and mild deflation. This was all due to the Great Depression and the First World War.