I guess the japanese Game would contain the same words used in the english versions. Assuming the english are just translated (though sometimes they do tend to add a bit extra or some like that when translating games)
I had the same idea as you a while back, I think playing japanese game boy games (which are really easy to get for your GBA emulator on the net). guessing it would be pretty good driller for the kana's. I do not know the amount of Kanji's you will encounter on your game though.
If you're a beginner, I would suggest learning a little more. since throwing yourself out in a whole game will become hard.
Also try go to the sub-forum here where there isn't used any english. sitting and trying to decipher the kanas/ translating others post will be a good drill for ya.
がんばって!