Japan did not had gas chambers, they did worst but they were not going after people because of their etnic groups but for other reasons.
Its unlike the Nazis that created a whole system to dispose of non arians, its perhaps the how the system was effiencient and inhuman that is so scary.
Japan reason to enter the war were similar to the reasons german entered WW I, they wanted their influence over the pacific, resources, markets and colonies.
And Servant of Eru you are very wrong on (at least) one thing ... Germany, England and the US had fighter jets around the end of the war and at least germany had a jet fighter proptotype before the war started, reason germany take so long to field their jet fighter (Me 262) was because hitler wanted it to be a dive bomber as well,.
A big issue with the Me 262 was it was very vunerable during landing and it was very easy to be shoot down by more convencional airplanes.
Also here is a little trivia, the japonese actualy had Me 262 at the end of the war since a U boat managed to deliver the plans and parts (the U boat that was to deliver the rest was sunk) and they were able to create a few but they were put in tunnels to be used during the invasion ... the nukes come and they were never used.