It'd be like if your team dominated mine in a season finale championship game, but half a year later mine beat yours in a 15-minute exhibition pre-season scrimmage that didn't really matter.
Afterwards Japan and the Soviet Union signed a Non-Agression Pact, and then Japan shifted their focus onto the US, and that’s when they became much more bellicose against the US. It also led to them officially joining the Axis with Germany, as they saw the opportunity to take Indochina and the Dutch East Indies, once Germany took care of The Netherlands and France.