To Aru Kagaku no Railgun dj - Unlucky Star

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) *Note: Includes 10 extra chapters.*

The story is set in a world where supernatural powers exist through science, and magic exists through religion. In the story, Touma Kamijou is an ordinary high school boy with terrible academic scores and a power called Imagine Breaker. Imagine Breaker can defeat any other power, but it also undermines Kamijou's own good luck. His Imagine Breaker's immense strength is literally immeasurable, so hapless Kamijou is listed at the supernatural level of 0. He happens to meet a girl in white hanging off his window balcony. The girl says she is being chased by sorcerers, and Kamijou learns that the girl is a Church of England nun whose memories have been forcibly replaced by Index-Librorum-Prohibitorum — the 103,000 forbidden texts of the Church.