Toaru Majutsu no Index: Gaiten Shoku

Set in a city of not only scientifically advanced superhuman students, but in a world where magic is also real. Kamijyo Touma's right hand, the Imagine Breaker, will negate all magic, psychic, or divine powers, as well as his own luck. One day he finds a young girl hanging on his balcony railing. She turns out to be a nun from the Church of England, and her mind has been implanted with the Index Librorum Prohibitorum—all the magical texts the Church has removed from circulation.

(Source: Wikipedia)

*Note: Includes 16 prologues, 18 epilogues, and 6 extras.*

Welcome to a world where mysticism and science collide, and supernatural powers are derived from either science or religion. At the heart of this world is Academy City, an advanced metropolis whose population is comprised mostly of students The majority of students are enrolled in the city's "Power Curriculum Program," where they must learn to master their latent psychic powers. Out of several million students, only seven are deemed powerful enough to have Level 5 status.

Meet Mikoto Misaka, the third most powerful Level 5 esper in Academy City. Together with her best friends Kuroko Shirai and the other members of Judgment, a student-run law enforcement agency, Mikoto delves deep into the dark heart of the scientific sprawl she calls home, and uncovers secrets she wishes she hadn't!

(Source: Seven Seas Entertainment)

*Notes:
\- Ten extra chapters are included.
\- Volume 5's special edition includes the volume "Giten Railgun".*

World War III is over. Touma disappears. Accelerator spends his days with Last Order and Misaka Worst. Shiage uses the secrets he gained in Russia as a bargaining chip. 

But this peace doesn't last long as the Freshmen arrive... 

(Source: Yen Press) 

*Note: Includes 21 prologues, 22 epilogues, and 2 extras.*

Science and magic exist side by side in this world.

This is the peak of the science side with a curriculum for espers, Academy City. In this city where 80% of the population are students, the season has finally come when all residents are excited and fidgety!

It's Christmas Eve.

Amidst the city showing a cheerful hustle and bustle, ordinary boy who can’t keep up with school, Kamijou Touma, also doesn’t intend to miss this event! He was hard at work in his supplementary lessons...

A backward glance from the default misfortune-prone bastard, the silver-haired sister freeloading in his dormitory, Index, in the heart pounding scene different from the usual, activates a new gluton skill!? While Kamijou tries to desperately stop that, Misaka Mikoto taken in by the Christmas Eve atmosphere appears before him.

Toaru Kagaku no Railgun: Arts and Sciences City SS is a short story in Arts and Sciences City that takes place in the time period between September 3rd to 10th. Academy City has a exchange program with the rest of the world that allows some students to travel for this week to other places, and some students are allowed into Academy City during this time.

Mikoto, Kuroko, Saten and Uiharu went to the Arts and Sciences City, made on a artificial island off the coast of California for a field trip. The Arts and Sciences City is known as a city that has cutting edge technology (in terms of the standards of the 'Outside' of Academy City - ie it is still far behind that of Academy City's), and is trying to take over Hollywood as the entertainment capital of the world. Stuntsmen and shows occur frequently at this city, and anything out of the ordinary is treated as another show. Due to the climate apart from sleeping everyone wears their swimsuits all the time.

(Source: Toaru Majutsu no Index Wiki)

Side-story novel to the Index/Railgun.
Misaka Mikoto is invited to Russia to demonstrate the abilities of Level Five in a shopping mall. There she meets a girl named Lessar.