Japan and formation of the Axis Powers

The Anti-Comintern Pact was concluded between Nazi Germany and the Empire of Japan (later to be joined by other countries) on November 25, 1936 and was directed against the Communist International (Comintern) in general, and the Soviet Union in particular. In case of an attack by the Soviet Union against Germany or Japan, the two countries agreed to consult on what measures to take "to safeguard their common interests". They also agreed that neither of them would make any political treaties with the Soviet Union.
On November 6, 1937, Italy also joined the pact, forming the group that would later be known as the Axis Powers. Italy's decision was more or less a reaction against the failed Stresa front, the Franco-British initiative of 1935 designed to keep Nazi Germany from extending beyond her present borders. In particular, both nations tried to block "German expansionism", especially the annexation of Austria, which was also in Italy's best interests to prevent.
In 1939, Adolf Hitler was preparing for war. Though he was hoping to acquire Poland without force (as he had annexed Austria the year before), Hitler was planning against the possibility of a two front war. Since fighting a two front war in World War I had split Germany's forces, it had weakened and undermined their offensive; thus, played a large role in Germany losing the First World War. Hitler was determined not to repeat the same mistakes. So, he planned ahead and made a pact with the Soviets - the Nazi-Soviet Non-Aggression Pact.
Japan continued to plot war against either the Soviet Union or the Western democracies, assuming Germany would occupy their potential European enemies.