Toaru Majutsu no Index Gaiden: Ace Misaka Mikoto tai Queen Shokuhou Misaki!!

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".*

The Tokiwadai student council election is approaching. Shokuhou Misaki, one of the leading candidates, is in the midst of an election campaign in spite of her own expectations due to the people around her and the fate of being the head of the largest clique...!! 

(Source: Toaru Wiki)