[lmm]

> Viewing Japanese only UTF-8 text is totally fine for Japanese localed Windows/Mac/(Linux but YMMV). So your case is to view the text on non-Japanese locale.

The issue is that realistically a certain proportion of customers are going to have the wrong locale setting or wrong default font set.

> It possibly have a problem but how SJIS solved the issue? What software switches font if it opens SJIS file? Is the app/format don't support specifying font/lang like HTML/Word?

Certainly Firefox will use a Japanese font by default for SJIS whereas it will use a generic (i.e. Chinese) font by default for UTF-8. I would expect most encoding-aware programs would do the same?

> If developer can switch reading charset on a file, then they can also switch font.

Sure, but it works both ways. And it's actually much easier for a lazy developer to ignore the font case because it's essentially only an issue for Japan. Whereas if you make a completely encoding-unaware program it will cause issues in much of Europe and all of Asia (well, it did pre-UTF8 anyway).