I hardly feel like I need to contribute to the "no, you can't translate an RPG in a week," thread, but. Here are some things to consider:
1) you want to do a good translation. this, of course, takes a while. if you seriously think it can be done "in a week," then you don't know anything about translation OR writing.
2) a lot of the difficulty of a large-scale RPG translation comes not from language issues but consistency issues. let's say you have a Key Item called the Dream Gem, but you could also read the kanji as Dreaming Stone or Wishing Jewel. EVERY TIME the Japanese characters for "Dream Gem" appear on the item screen, in quest descriptions, in the battle area, in NPC dialogue, in story cinemas, you MUST translate it THE SAME WAY. Stuff like that can take a LONG time to establish and double and triple check.
3) RPGs have a lot more text than you probably realize. there's a lot of minigame, sidequest, townsperson dialogue most people will never see. well, the people translating it have to see it all.
4) the English version is not "the Japanese version only in English." it is, effectively, a brand new game that has to be tested and retested from scratch.
5) translating the text is like 5% of the overall work of a localization. resolving issues with the original development team, clarifying things that can be read in multiple ways, formatting the text according to the system used by the developers, actually inserting the new text into the game code, testing the translated game, establishing the overseas version of the packaging, etc. etc.. all these steps take time.
6) even once all this is done, the publisher in a different territory may decide to wait a few months to actually publish it, for no reason other than this year vs. last year on the budget sheets, waiting for the holiday season, pure caprice, etc.
That said, you're welcome to learn Japanese, assembly language, and C code and to prove me wrong. Hell, I'm feeling generous; you can have ten days.