Toaru Majutsu no Index

A city exists where students with superhuman abilities are trained through science, and magic is a real force in the world. A boy named Touma Kamijou possesses a unique ability in his right hand called the Imagine Breaker, which can nullify magic, psychic, or divine powers, though it does not affect his own tendency to encounter misfortune. One day, he discovers a girl clinging to his balcony. She is later revealed to be a nun affiliated with the Church of England, whose mind has been altered to contain the Index-Librorum-Prohibitorum—a compilation of magical knowledge the Church has suppressed.