What would be appropriate expressions or idioms to convey the typical English response:
What's it to you?
(in a sense that goes somewhere between "None of your business" and "This is not your problem")
The best I can think of is
あなたには関係ない. I am looking for other possibly softer, more polite ways of expressing the same idea.
(as an aside, if you have less polite, more direct, I am also curious)
PS: Before anybody comments: I realise that any variation on this will sound too direct and potentially rude for many situations in Japan, however softly it is formulated. But the general idea is to be trenchant, in situations which might call for it... so no need to dwell on the rudeness aspect too much.
Edit: tough to pick from many overlapping (quality) answers, but in the end, I think Rey's encompassed exactly the nuance(s) I was interested in. Thanks everybody for the great suggestions!