The Index Arc is the first major story arc introduced in the Toaru Majutsu no Index series. The arc introduces Kamijou Touma, a young man with the mysterious power of the Imagine Breaker, living in the scientifically advanced Academy City – home of the espers. The arc focuses on Touma meeting a mysterious nun by the name of Index which pulls him into the mysterious world of magic that coexists with science, and his struggles with the magicians who wishes to take Index. This arc occurs near the end of the Level Upper Arc in the Toaru Kagaku no Railgun sidestory.