If you enjoyed the "Musou-style" (one-vs-many) combat of the original game, this repack is a major upgrade. It breathes new life into the aging PSP title by adding content that the original developers never did.
Summary
You likely downloaded a fake repack. Find a version where the ISO size is between 800 MB – 1.1 GB (anything smaller is usually just a compressed original).
and other community creators have transformed the base game into a "sequel" experience through: New Playable Characters:
to make the combat feel more modern on mobile and PC emulators. Enhanced Textures