To be clear, Naruto Shippuden: Ultimate Ninja Storm 2 was never officially released for the PSP. It is a console game for platforms like PlayStation 3, Xbox 360, and PC.
This leads to the dark comedy of the search result page. For every legitimate fan patch, there are fifty links to ad-ridden “ROM sites” promising the file but delivering malware disguised as a DLL file. The journey involves closing pop-up ads claiming your Android has a virus, deciphering “Click here to generate link,” and eventually downloading a 1.5GB zip that contains a broken EBOOT.PBP and a text file that just says “lol.” It is the digital equivalent of falling for a substitution jutsu.
Because Storm 2 does not exist as a native PSP file, the "PPSSPP version" found online is typically a modded ISO.