why did this happened ?
The Japanese empire started on 1930's, were it started invading countries like china. Its empire extended from Manchuria to the Philippines. Japan started invading other countries because it needed resources and for geopolitical position. Well China was fighting to survive in the war after Japan successfully invading other countries they thought they will come for them. If Japan wins the war it will gain its access to china for its resources but if Japan looses it will loose the chance of gaining china's resources but china will loose its land.