Ensure your saves are backed up, your locale is set to Japanese, and dive back into the Tohno mansion. Disclaimer: This guide is for educational purposes. Always scan downloaded .sav files for malware (though rare for VNs, it is possible).
Do not lose your progress. Copy the original savedata folder to your desktop. tsukihime save file
Drag the downloaded .sav files into the folder. If asked to overwrite, click "Yes." Ensure your saves are backed up, your locale
Remember: A save file unlocks content, but it cannot replace the emotional impact of reading the "Ciel's True End" for the first time. Use these files to skip tedium, not tragedy. Do not lose your progress
This is a pro tip. Sometimes the game ignores new saves. Right-click the savedata folder > Properties > Uncheck "Read-only" > Apply to all subfolders.