Without any info about the document itself and the images we can't realyl tell you much and I don't do Japanese. Still, it seems to me that this is the color profile conversion warning and that in itself could be the answer. Apple's Preview isn't great in displaying print-centric/ print-ready documents and it may simply be that it doesn't know what to do with the images and color spaces. If that's the case, then there's nothing to worry. Install Acrobat/ Adobe Reader to preview such documents correctly.