Can you recommend some good 'a certain magical index fanfic'?

One popular 'a certain magical index fanfic' is 'Index's New World'. It has an engaging plot that takes the characters on a different kind of adventure. Another is 'The Esper's Secret', which delves deeper into the backstories of the espers. There's also 'A Certain Magical Change' that offers a fresh perspective on the relationships between the characters.

Well, 'Railgun's Adventure in Index World' is a great 'a certain magical index fanfic'. It combines the elements of the Railgun series with the Index world in a really interesting way. Then there's 'The Magical Academy Reimagined', which creates a new setting within the 'a certain magical index' universe and tells a story full of mystery and action. And 'Kamijou's Hidden Power' is also quite good as it focuses on the potential of the main character in a unique way.

I would recommend 'The Dark Side of Academy City' as a 'a certain magical index fanfic'. It explores the seedy underbelly of the Academy City that is not often shown in the original. 'The Esper Alliance' is another one, where different espers team up for a common goal in a really exciting story. Also, 'A Certain Magical Romance' is a nice read if you're interested in the romantic aspects between the characters in the 'a certain magical index' world.