: The primary antagonist of this arc, introduced as a ruthless combatant.
: This is the first time the audience learns about the "Tree Diagram" calculations and the horrific scale of the experiment. To Aru Majutsu no Index Episode 10
: Follows Touma and Index on a flight to the United Kingdom , where they must thwart a terrorist hijacking. : The primary antagonist of this arc, introduced
Following the loss of his memories, Touma Kamijou encounters Mikoto Misaka for the first time. He subsequently meets a young girl who looks identical to Mikoto, identified as . Throughout the episode, Touma spends time with this "Sister," experiencing a series of comedic and slice-of-life moments. identified as . Throughout the episode