If WinRAR gives you a "Checksum Error" during extraction, it usually means Part 2 (or another part) was corrupted during download and needs to be re-downloaded.

The game uses a vibrant cel-shaded style to mimic the original anime.

Searching for specific file parts like usually indicates you are looking to complete a multi-part archive for One Piece: Unlimited World Red . Understanding Multi-Part RAR Files

When a large game is uploaded to sites like ApunKaGames, it is often split into smaller "parts" (Part 1, Part 2, etc.) to make downloading easier and to stay within file size limits.

You cannot extract the game using only "Part 2." You must have all parts (e.g., Part 1 through Part 10) in the same folder.