Because WinZip always make mojibake.
But I prefer Shift JIS.So,Unicode transrcipting will didn't work,but a romanji converter plugin for the compressor programs(WinZip or 7Zip)
is another nice method to prevent mojibake.It can handle ANSI(and every codesets) because is converts あ to a.Try to make it!
OFF:7Zip can handle hiragana correctly on a romanji computer?
ON:If it(7Z) does nothing to mojibake,this plugin might be the help of the romanji users.