If the archive is 99% intact and you cannot find a new UPD file:

Before extracting, right-click the .rar and select (or your antivirus). Because this is a fragmented file, malware scanners cannot see inside the .rar fully, but they can flag the container itself as suspicious.

Tools like WinRAR, 7-Zip, or The Unarchiver are required to handle multi-part RAR files.

This typically refers to FC2 Content Market, a Japanese platform where creators can sell Pay-Per-View (PPV) content.