The original game stores its progress directly inside the installation folder rather than the Windows AppData directory. Look for files labeled: gamedata.dat

If playing via the "Tsukiweb" browser version, saves are stored in your browser's local storage . It is highly recommended to use the Export button in the advanced settings to download a physical backup to your PC, as browser data can be cleared by the system. Tsukihime Remake (A piece of blue glass moon) Save Data