Episode Title:
Impostor (Replica).
Episode Description:
Mikoto is being stalked by Mitsuki Unabara, the Tokiwadai Middle School principal's grandson, ever since the last week of summer vacation. When she sees Tōma passing by with his friends, she pretends to go on a date with Tōma. After an embarrassing mix-up with hot dogs, Tōma learns that less than ten of the Sisters remain at Academy City while the rest went overseas for treatment. Mikoto later goes to a restaurant to get food while Tōma converses with Unabara outside. Tōma sees an identical Unabara running into the restaurant, injured and warning Mikoto about an approaching danger, which means Tōma was talking to an impostor, who hits him from behind. As Tōma flees, Index reveals by phone that the impostor duplicated Unabara's appearance by using Aztecan sorcery, wielding an obsidian spearhead replicating the lance of Tlahuizcalpantecuhtli. When Tōma is forced to fight him at a construction site, the impostor reveals that his mission was to become close to Tōma's friends to prevent the formation of the Kamijō Forces, in which Tōma would ultimately lead a group of mages and espers who fear will destroy the truce between them. The impostor, who had fallen in love with Mikoto, decided to protect her by killing Tōma. However, after being defeated and severely injured by falling steel beams, the impostor asks Tōma to promise him to protect Mikoto since Tōma and his friends will continue to be targeted. Unknown to both of them, Mikoto is listening nearby and is embarrassed to hear Tōma's answer.
