In a world where supernatural abilities are intertwined with science and magic is entwined with faith, the tale follows Touma Kamijou, an average high school student with abysmal grades and an ability known as Imagine Breaker. Despite its capability to nullify any power, Imagine Breaker also negates Kamijou's own luck. Classified as a supernatural level 0 due to the incomprehensible potency of his ability, Kamijou's life takes a turn when he encounters a white-clad girl perched on his balcony. This girl, pursued by sorcerers, reveals herself as a Church of England nun whose memories have been replaced with Index-Librorum-Prohibitorum — the Church's collection of 103,000 forbidden texts.