Toaru Majutsu no Index
Set in a city of scientifically advanced superhuman students, but in a world where magic is also real. Touma Kamijouï¿½s right hand, the Imagine Breaker, will negate all magic, psychic, or divine powers, but not his own bad 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.