This is the most notorious issue. You save the game, everything works fine. You turn off the PSP, turn it back on, and the save file icon is a red "Corrupted Data" block. The 3rd Birthday uses an aggressive anti-cheat/anti-save editing feature. If the game detects any discrepancy in the save file’s checksum, it permanently bricks the file.
Use PPSSPP → Tools → Cheat Search → Search exact BP number → Play → Gain BP → Next search → Modify. 3rd Birthday Psp Save Data
The 3rd Birthday (PSP) – 100% Complete Save Data | All Episodes, Costumes, Weapons & Bonus Unlocks This is the most notorious issue
[Your Site Name] Category: PSP / Square Enix Guides Read Time: 8 Minutes turn it back on