So i ran out of luck trying to decode these files with sharpziplib. I switched to dotnetzip and changed the encoding to 932 which sharpziplib doesnt seem to have when decompressing? Im gonna answer my own question as I dont see a lot of references regarding this issue and for other people who might encounter this issue in the future.
 using (ZipFile archive = new ZipFile(archiveFilenameIn, Encoding.GetEncoding(932)))
                {
                    archive.Password = password;
                    archive.Encryption = EncryptionAlgorithm.PkzipWeak; 
                    archive.StatusMessageTextWriter = Console.Out;
                    String fullZipToPath = Path.Combine(outFolder, Path.GetFileNameWithoutExtension(archiveFilenameIn));
                    //string directoryName = Path.GetDirectoryName(fullZipToPath);
                    if (fullZipToPath.Length > 0)
                        Directory.CreateDirectory(fullZipToPath);
                    archive.ExtractAll(fullZipToPath, ExtractExistingFileAction.Throw);
                }
EDIT: So i played around with sharpziplib and it actually turned out that i can set the default code page. It was working fine after that.
ZipConstants.DefaultCodePage = 932;