How to fix naming issue: use WinRAR for files that contain japanese text. This works both ways, conserves jap filenames when storing, AND lets you fix broken encoding when extracting. (Open a broken zip in WinRAR and press ctrl-e, select 932 Japanese Shift-JIS, extract like normal)
Note: You can still use other apps like 7z to *store* as other formats, but winrar itself is needed to fix already broken ones. It's specifically .zip format that breaks asian text in filenames.