The Kazakiri Hyouka Arc is a story arc in the Toaru Majutsu no Index storyline. It primarily focuses on Kazakiri Hyouka, a physical manifestation of all espers AIM diffusion fields in Academy City and the key of the Imaginary Number District–Five Elements Institution, manifesting in the world. Being the first story arc that has a collision between magic and science elements, it marks important elements that are central to the whole Toaru Majutsu no Index storyline, which are Aleister Crowley and his plans and the importance of Kamijou Touma and his Imagine Breaker.