Kamijo is a student in Academy City, a place where science is harnessed to cultivate supernatural abilities. Despite being one of the weaker students, Kamijo has a big heart, which proves fortunate for a young nun named Index. She is fleeing from a sorcery society eager to obtain the incredible 103,000 volumes of magical knowledge she holds in her memory. When Index crosses paths with Kamijo, she discovers a loyal friend and protector. Although Kamijo may not be the strongest, he possesses a unique ability in his right hand known as the Imagine Breaker, which can nullify the powers of others. As both scientists and sorcerers close in on them, the Imagine Breaker becomes a crucial asset, but it is Kamijo’s unwavering dedication to Index that truly serves as his most powerful tool in ensuring her safety.