Japan is a culture of indirect communication. When I first started learning Japanese, my teachers never failed to stress this. The language has countless examples of indirect communication via subtle queues that you just have to discern and somehow figure out. Japanese culture values politeness in speech, so indirect is always considered far more polite than direct, especially when it comes to something like refusal.
You get invited to a karaoke party on Friday, but you just don't wanna go. Perhaps you don't like karaoke or don't really enjoy the company of the people that invited you.
I had always been taught to refuse using expressions like these:
The conditions are not good, so...
Karaoke is a bit...
Friday is a bit...
I have another plan that day, so...
Thank you so much for inviting me, but I'm sorry. I have a schedule conflict on that day, so...
The pervasive theme is the "..." pattern, which is sort of a "fill in the blank." Called 点・点・点 in Japanese, it hints at the refusal without directly stating it, preventing hurting the other person's feelings and making the social situation more awkward. The general idea is that the other person usually gets the hint. It's also common to soften the refusal even more by prefacing it with something like すみませんが、or 申し訳ございませんが、which is basically apologizing before the indirect "fill in the blank" refusal.
This communication through subtle hints is the Japanese I've always known and loved. It is not just the essence of the Japanese language; it is the life-blood of the Japanese culture.
But recently I actually got scolded by a (young) Japanese acquaintance for not being more direct. WTF?! You can't do that! My entire world tumbled down. Apparently there exists this underworld Japanese where unruly people break the rules and speak rudely, like "Pleasure Island" from "Pinocchio." Damn our Japanese language instructors for always teaching us to be so polite!
I'm not entirely sure, but direct refusal in Japanese seems to be all the rage right now, as I find several blog posts related to this trending expression:
Although I'm not a native speaker, this expression actually made me laugh because while it is technically polite (it uses an honorific verb), its brevity comes across as terse in my humble opinion. Obviously a native speaker would be more qualified to comment, but it reminded me of a short story by Herman Melville titled, "Bartleby, the Scrivener" where the main character refuses anything and everything using the expression, "I would prefer not to."
There could be deep-seated merit to this expression, though. Without any room for misinterpretation, it certainly gets the refusal job done quickly and forcefully--like ripping off a bandage.
After consulting with some native Japanese friends via Facebook, I compiled this list of handy refusal expressions. Please note how they get longer as they get more polite, but these expressions are still more direct than the usual "..." indirect pattern.
I respectfully decline.
I'm terribly sorry, but I respectfully decline.
I'm terribly sorry, but I respectfully decline this meeting with your company.