Kamijo is a student in Academy City, where people use science to develop supernatural abilities. The guy’s got a lot of heart – luckily for a young nun named Index. She’s on the run from a sorcery society that covets the astonishing 103,000 volumes of magical knowledge stored in her memory. When Index stumbles into Kamijo’s life, she find a faithful friend and protector, and while Kamijo’s easily the weakest kid in Academy City, he’s got something else going for him: the Imagine Breaker, an unexplainable power stored in his right hand that negates the powers of others. With scientists and sorcerers attacking from all sides, the Imagine Breaker will definitely come in handy – but it’s Kamijo’s loyalty to Index that will be his greatest weapon in the fight to keep her safe.
In the year 2138, virtual reality gaming is booming. Yggdrasil, a popular online game is quietly shut down one day. However, one player named Momonga decides to not log out. Momonga is then transformed into the image of a skeleton as “the most powerful wizard.” The world continues to change, with non-player characters (NPCs) beginning to feel emotion. Having no parents, friends, or place in society, this ordinary young man Momonga then strives to take over the new world the game has become.
The film’s story begins when Arata inadvertently touches “Hermes Apocrypha,” Lilith’s Grimoire. Suddenly, he is enveloped by a bright white light, and a girl appears before him. She calls herself Lilim, and treats both Arata and Lilith as her parents. At the same time she appears, something changes in the world. The forbidden Eternal Library awakens. In the Library is sealed the ultimate culmination of Alchemy, the White Demon Lord. The White Demon Lord plots to eliminate Arata and the Trinity Seven to usurp the position of Demon Lord. Bristling with untold power, the White Demon Lord attacks Arata, and triggers a desperate crisis where Arata and the Trinity Seven must save the world in this last battle.