the way I remember it was that Germany, Austria/Hungary and Russia started it over that squabble about investigating the assassination of an arch-duke. France, England and everyone else just piled on...
That's the part that we (European, UK, US) learn about b/c it is what affected us the most. In Asia, they learn more about the effect that the Japanese had (and remember, they started up right at the very beginning of the war) over China, Mongolia, etc and the hegemony they had there.
It's all a matter of viewpoint I guess.