The girls of Academy City are heading back for their February 23, 2013 return date in anime movie A Certain Magical Index: The Miracle of Endymion. With the combination of fantasy and sci-fi that made the series a favorite in both genre categories, the plot by author Kazuma Kamachi concerns the involvement of three new characters with the construction of a space elevator.
The primary original character is Arisa Nago, a Level 0 (person with no powers) girl who Index and Kamijou meet at the outset of the movie, and is subsequently revealed to be targeted by Stiyl Magnus and his team of magicians.
Toaru Majutsu no Index wikia, describes the plot:
Academy City’s space elevator Endymion. One day as its completion nears, Touma and Index meet a Level 0 girl named Nago Arisa. Index and Arisa have a mysterious connection in their ravenous appetites. While the three are enjoying their time afterschool, Stiyl (who has brought in some other magicians) suddenly attacks. His target is Arisa. Why is a member of the science side like her being targeted by the magic side? With the attack form the magic side underway, Academy City deploys a unit meant to maintain order led by its female leader Shutaura. As the situation developing around Touma, Index, and Arisa grows more and more confused, Stiyl says, “That girl could likely cause a war between the magic side and the science side.”
When science and magic cross paths, the story begins with Endymion as its stage!