Kamijo meets Index, who is on the run from a magic society that wants the library of forbidden knowledge stored in her memory. Later, Kamijo is shocked to find Index at his house - bleeding and accompanied by a strange man.
Kamijo tangles with Stiyl, upset with the magician's rough behavior toward Index. When quick thinking allows Kamijo and Index to escape, they head to the one person that might be able to help them.
Kamijo learns more about Index's history with Necessarius, the Church of Necessary Evil. Later, after a trip to the bathhouse leads to an argument with Index, Kamijo finds himself in the company of a mysterious stranger.
Kaori Kanzaki confronts Kamijo, demanding that he hand over Index. Kamijo is wounded in the ensuing scuffle - and when he wakes up a few days later, Index offers to take drastic measures to protect him from further harm.
When Kamijo springs into action to prevent Kanzaki and Stiyl from erasing Index's memory, he learns there's a chance that the Church was lying about the threat to Index's life all along!
Kamijo succeeds in eliminating the magical threat to Index's life. Unfortunately, his memory is erased in the process! Later, Stiyl's boss orders him to work with Kamijo. Their assignment: Find "Deep Blood."
Stiyl tells Kamijo (who has no memory of the sorcerer) about his plan to raid Misawa Prep School in order to rescue a young girl who wields a vampire-summoning power known as Deep Blood.
Kamijo and Stiyl quickly fall under attack after infiltrating Misawa Prep School! During the raid, Kamijo runs into the girl they hoped to rescue - but there's a chance she isn't interested in leaving the campus!
Aureolus finds his plan to turn Index into a vampire thwarted and learns that Kamijo has already saved Index's memory. Overwhelmed by anger and jealousy, the alchemist attacks Kamijo in a fit of murderous rage.
Kamijo senses something odd about the relationship shared by Mikoto and Misaka, who appears to be Mikoto's twin. Later, after a friendly meeting with Kamijo, Misaka has a much more intense encounter with Accelerator.
Kamijo is surprised - and confused - by the sudden arrival of yet another Misaka doppelganger. When the new look-alike explains why there are so many Mikotos running around, Kamijo decides to investigate.
Kamijo learns that thousands of Mikoto clones were created for one simple, violent reason. Now that her look-alikes are dying off, the real Mikoto vows to save the rest of her doppelgangers by making the ultimate sacrifice.
During a trip the bathhouse, Komoe offers insight on the awakening of esper powers to Index and Himegami. Later, Mikoto is skeptical when Kamijo volunteers to take on Accelerator in battle.
