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 FromEdit

Major EventsEdit


By order of appearance:

New CharactersEdit


New AbilitiesEdit


New LocationsEdit


  • 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.


Cultural ReferencesEdit

Differences in AdaptationEdit

Animation TriviaEdit


# Title Time Scene & Notes
ROAR Opening
Unverified Track
Unverified Track Eyecatch
Unverified Track
Dog Fight Accelerator vs. Touma[1]
Deep Snow Accelerator realizes what he should do[1]
Unverified Track
Owaranai Uta Ending
ROAR (Preview Version) Preview

Unanswered QuestionsEdit


  • 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.



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