If you only have the original Japanese ISO, you’ll need the fan patch.
Here’s a helpful article-style guide for finding and playing the English-patched version of Toaru Majutsu no Index (A Certain Magical Index) for PSP. Toaru Majutsu no Index PSP -JPN- ISO -English P...
The combination of the and the English fan translation patch opens up a forgotten chapter of the Index universe. For years, English-speaking fans could only watch Japanese playthroughs on NicoNico or YouTube, wondering what the alternate story held. Now, with a bit of technical know-how, a physical copy, and the community’s hard work, you can experience “Route of Kamijou” in full. If you only have the original Japanese ISO,
All UI elements, including options and move lists, are translated. Dialogue: The main story mode is fully readable in English. For years, English-speaking fans could only watch Japanese
Unfortunately, the original "Toaru Majutsu no Index PSP -JPN- ISO" game was released only in Japan, and as such, it does not support English language. This can be a significant barrier for fans of the series who want to experience the game but are not fluent in Japanese.