I'm not sure what you mean by an image file - an ISO file or a screen image? I'm guessing, probably wrongly, that you want a screen image. I've provided two: the first is ImgBurn with the garbaged file names; the second is the proper file name from 2xexplorer, a freebie European language file manager that works perfectly with Japanese. I don't think you need a real ISO file with a unicode name to check your code. Any random file with a multibyte/unicode file name and an ISO extension, even if it isn't a real ISO file should allow you to trace the error. Or you can take an existing ISO file that you have, copy a bit of Chinese, Japanese, or Korean text from somewhere. Replace your existing file name with this bit of text and play around with it.
Given that Winblows since 2000 on is unicode based, I would assume there is some incentive for professional programmers to learn how to code properly for international usage. The Microsoft MSN developer site has a number of items on proper programming for multi-language usage.