Toaru Majutsu no Index Wiki

A Reason to Protect (守る理由 Mamoru Riyū?) is the twentieth episode of the third season of the Toaru Majutsu no Index anime series. It was broadcast on February 22nd 2019, and was directed by Nogami Yoshiyuki, was storyboarded by Watanabe Takashi, and the script written by Kingetsu Ryunosuke.


Black wings cast a hue over the snowy plain. Blood-soaked fists clench tightly. The mightiest and the lowliest now once again clash.

Adapted From

Major Events


By order of appearance:

New Characters


New Abilities


New Locations


  • The voice actress of the unnamed mother is Matsuda Risae.
  • The voice actress of the unnamed daughter is Nukui Yuka.
  • The voice actor of the unnamed driver is Yamane Masashi.
  • The voice actor of the unnamed operator is Sugisaki Ryō.
  • The Maiden of Versailles is Elizalina's sister.


Cultural References

Differences in Adaptation

  • In the novel, Accelerator makes two theories about Touma's powers. The first is about his Imagine Breaker, which couldn't completely negate his black wings, unlike what happens in the anime. He theorizes that he can't negate, at least instantly, a too large amount of power. The second is about Touma's Precognition, an ability he developed subconsciously through his numerous battles, that's why he can anticipate the movements of Accelerator's black wings, but also match against Railgun's speed for example. According to Accelerator, these two abilities combined make him strong and look terrifying.[1]
  • In the novel, Accelerator attacked Touma with 100 black wings from all angles, but Touma managed to survive by catching one of the black wings, thanks to the weakness of Imagine Breaker which couldn't completely negate it, and make Accelerator lose his balance.[1]
  • In the novel, Accelerator remains at a safe distance and attack with his black wings while in the anime their fight turns into a fist fight.[1]
  • In the novel, Misaka searches classified informations of Academy City's Bank and learns that they intend to attack Touma and keep him alive with Dark Legacy, which convinces her to help him in Russia.[2]

Animation Trivia


# Title Time Scene & Notes
ROAR Opening
Unverified Track
Unverified Track Eyecatch
Unverified Track
Dog Fight Accelerator vs. Touma[3]
Deep Snow Accelerator realizes what he should do[3]
Unverified Track
Owaranai Uta Ending
ROAR (Preview Version) Preview

Unanswered Questions


  • Accelerator" You are the hero who saved all the Sisters! "  - said to Touma after meeting him for the second time.
  • Touma: "If you wanted to protect that kid, then do it with you head held high! Be pround now, you are able to keep her safe." - said to Accelerator.
  • Accelerator"I wanted to defend her, no matter what. So I rush headlong down the path I could choose - the path of evil - and got very good at being evil, but... the guy who never even considered whether he was good or evil turns out to be the strongest one. " - said to himself after Touma defeated him.
  • Touma: "Sure, I'm a real lowlife. A no-account jerk who's been deceiving Index. But even if I am, it's not Fiamma that I should be bowing to." - said to himself.


This section requires expansion



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