I know this big iM@S fan that knows some Japanese and can help me with what the girls are saying, but I don't really want to overuse his kindness since he's busy with life and all that. So I can only do the basic things and get the basic information on them into the wikia. I want to hear everyone's opinion on the stuff that I do too, so that I can learn from the mistakes that people tell me and improve on it. ^^
I'm taking Japanese classes right now, and I can admit it helps...well very little. Maybe I don't know enough yet, but I don't think you need to know that much Japanese to play.
The one area I've seen improvement in though is sort of irrelevant now as it relates to iDOLM@STER 1's vocal game. I've found that I can more easily find what's wrong with the lyrics but that's all.
I can understand some of the songs a little bit better, but I don't think that really helps with gameplay.
I think you'll learn some basic phrases and kanji if you play though. ^^