Since the game is primarily played via the original Japanese PC release (often with the Voice Patch and English Translation patch), save files are widely shared within the Type-Moon community. Reliable Sources

For years, English-speaking fans were locked out of the game until the Mirror Moon translation patch was released. Often, players would start the game, apply a patch, and realize their old save files were incompatible or corrupted due to script changes. This necessitated the hunt for "clean" save files compatible with the English patch version.