The fourth arc of ''Literature/ACertainMagicalIndex'', consisting of volume 4 of the light novels and episodes 15-17 of the anime. This story arc was omitted from the manga for some reason, even through some important plot points happen here.

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* AdaptedOut: The portion of the Angel Fall investigation surrounding the serial killer, Hino Jinsaku, whom was believed to be the culprit that casted Angel Fall, was cut from the anime adaptation.
* ADayInTheLimelight: For Kaori, Motoharu, and Touma's family.
* ArcVillain: A fallen angel naming itself Misha[[note]]Later revealed to have been Archangel Gabriel[[/note]] who takes the form of Sasha Kreutzev due to Angel Fall
* BarelyThereSwimwear: The swimsuit Touma's mother wears.
* BrainBleach[=/=]FanDisservice: Seeing "Index" in such a scanty swimsuit and then "Pierce" in a girl's swimsuit.
* CantBatheWithoutAWeapon: Kaori carries her sword everywhere with her, even when she bathes.
* ContrivedCoincidence: The Angel Fall spell was cast accidentally by Touma's father. Tsuchimikado notes that with the amount of occult artifacts he had collected, casting ''some'' spell was inevitable, and it's a miracle it was a relatively benign spell like Angel Fall.
* GodzillaThreshold: Gabriel is such a threat that Kaori reveals her magic name right away instead of as a last resort.
* TheGreatestStoryNeverTold: Touma's ordeal through this entire arc is only known by Kaori and Motoharu.
* MikeNelsonDestroyerOfWorlds: Toya Kamijou almost caused the world to be destroyed, and he never learns this.
* MomentKiller: Touma intentionally stops his parents from having sex, since his mother looks like Index at the moment.
* OurAngelsAreDifferent: This is the first story where we meet an angel, the titular creature that fell from Heaven due to the spell. While it attempts to return in a non-violent way, in the end it will have no choice but to cause massive destruction to fuel its re-ascent.
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