if I activate the Korganizer Plugin Holidays and choose ja (Japanese) I get the Holidays shifted + 1 day. for example "Umi no Hi" [Ocean's Day] should be Monday 19th 2004, but it shows on Tuesday 20th 2004. I think this is a KDE bug, as it also shows on debian, Reproducible: Always Steps to Reproduce: 1. 2. 3.
You already reported this bug at kde bugzilla: http://bugs.kde.org/show_bug.cgi?id=84987 so I think there's no need to keep it open here too...
Thanks Gregorio.