It seems that an answer here must hinge more on how you define fascism, than on any facts about Japan in the thirties. The strictest possible sense of 'Fascism' is the Italian political movement that called itself that, from the 'fasces' it used for its emblem - an axe surrounded by rods, allegedly carried by Roman lictors so they could mete out capital and corporal punishment on the spot. The broadest sense without going to "politics I don't like" is something on the order of "authoritarian politics emphasizing military strength and self-sufficiency, with a side order of imposing "castle peace" through state-mediated negotiations between large organisations representing economic interests". (Whew.) I've left out any racial aspect, which was more a feature of the specifically German fascism (other than the generic background-level racism that was endemic everywhere), and also the futurist speed-power-sleekness aesthetic; these don't seem to me to be defining characteristics.
Clearly Imperial Japan does not meet the first, narrow definition; as for the second, it was definitely authoritarian, its expansion was specifically motivated by access to resources, and it might be possible to shoehorn the zaibatsu into the "organisations representing economic interests" - but I don't think you'd be wise to do so in this context; the idea of Fascism was specifically that the workers should also have a voice at the table. So during writing this I've talked myself out of considering Imperial Japan as a fascist state; they're missing what I consider an essential ingredient, the theoretical framework for organising the economy for war. But someone who considered a different aspect as the essential one could reach a different answer.
I think the others here have done a better job than I could have done.
I just want to point out one minor thing.
Basically, are you trying to describe Japan in the 30s and 40s or are you trying to define it? The problem with language is that it seeks to report but generally ends up classifying.
I would recommend for reading:
Total Empire
War Without Mercy
Embracing Defeat
Hirohito and the Making of Modern Japan