Toaru Majutsu no Index Episode 21

"Counter Stop" is the twenty-first episode of the Toaru Majutsu no Index anime series, and the first episode of the Kazakiri Hyouka Arc. It was first broadcast on March 1, 2009, and was directed Yanagi Shinsuke, storyboarded by Yanagisawa Tetsuya, and the script written by Nishizono Satoru.

Touma's long summer vacation that began with his encounter with Index is ended and the semester begins. In Touma's class, Himegami Aisa who was freeloading in Komoe's house appears as a transfer student. Meanwhile, entrusted to stay at home, Index discovers that lunch wasn't provided for her and reaches Touma's classroom and is immediately kicked out by Komoe. She wanders towards the cafeteria and comes upon a vending machine. Predictably, she does not know how to make a purchase until she is aided by Kazakiri Hyouka, who appears casually before her. Their relationship deepens and Index becomes friends with Hyouka. In the peaceful Academy City, a magician is confirmed to have infiltrated the city.

Adapted From

 * Prologue, Chapter 1 (including Between the Lines 1), & Chapter 2 Parts 1, 3 & 5

Adapted To

 * Game: Toaru Majutsu no Index: Imaginary Fest Main Story

Major Events

 * Academy City's second school semester begins.
 * Himegami Aisa transfers to a certain high school.
 * Index and Touma meet Kazakiri Hyouka.
 * Shirai Kuroko confronts Sherry Cromwell but is unable to subdue her.

Characters
By order of appearance
 * Kamijou Touma
 * Index
 * Sphynx
 * Misaka Mikoto
 * Tsukuyomi Komoe
 * Tsuchimikado Motoharu
 * Aleister Crowley
 * Himegami Aisa
 * Shirai Kuroko

New Characters

 * Musujime Awaki
 * Sherry Cromwell
 * Kazakiri Hyouka
 * Yomikawa Aiho

Abilities

 * Teleport - Shirai Kuroko, Level 4
 * Electromaster (Railgun-variant) - Misaka Mikoto, Level 5

New Abilities

 * AIM detection (mentioned, hypothesized to exist by Touma)
 * Move Point - Musujime Awaki, Level 4
 * Golem Ellis - Pratical Kabbalah, Sherry Cromwell

Locations

 * Academy City
 * School District 7
 * Kamijou Residence
 * A Certain High School
 * Windowless Building

New Locations

 * School District 7 Underground Shopping Center

Trivia

 * Due to Yamisaka Ouma's story being transferred to the second season of Toaru Majutsu no Index, a continuity error exists in this episode, specifically, Touma's room remaining intact, though this event is not mentioned again in the novels as well.
 * When Index picks up Sphynx and rolls around the floor, she once hums A Certain Tune.
 * This is the first introduction of AIM in the series.
 * The mysterious Imaginary Number District is introduced.
 * Telesma is first mentioned in the series.
 * Aisa being a girl who goes unnoticed, would later become a recurring joke in every Toaru Majutsu no Index-related media she would appear in. This would be prominent in the Toaru Majutsu no Index-tan specials, poking fun on her apparent lack of notability.
 * This marks the very first time espers and magicians, if one does not take Tsuchimikado Motoharu into account, do battle with each other.

Referbacks

 * Touma references his memory loss again back in episode 6.

Cultural References

 * The talk regarding AIM and detecting it, references common tropes in fighting manga and anime, most importantly, a character detecting and measuring another character's power.
 * The is referenced by Index.
 * In the scene outside of school, after Aisa is focused on for the first time after her introduction to the class, and her noticing Touma and company, there are two background characters that walk by. The characters look similar to Fukuzawa Yumi and Ogasawara Sachiko of .
 * The popular series of books is referenced during the episode as a book for learing about AIM diffusion fields.
 * Several terms from Jewish mythology and Kabbalism is referenced in this episode, such as the Golem,, and the origin of Man, and their relations with angels. Mos specifically, the are referenced.

Differences in Adaptation

 * Mikoto did not use her iron sand whip in this episode and she only used her Railgun against the golem. Originally, she used both of them to free Kuroko from golem Ellis.

Animation Trivia

 * Komoe's car is the only traditionally rendered during its appearance.
 * Mikoto would need to be pretty quick or the coin have been flipped very high, for her to make a pose for her Railgun.