A Certain Magical Index

Hamazura must defend the members of ITEM against a new threat from Academy City. Accelerator acquires the final piece of the puzzle to a cure for Last Order. The showdown between Fiamma and Kamijo becomes even more intense.

As Kamijo and Sasha look on, Hyoka rushes in to stop the archangel's rampage. Accelerator joins the battle as well, with a newfound purpose. Acqua has his own strategy to weaken the archangel's power, though at great cost to himself.

Accelerator begins finding clues about the parchment he is carrying. Hamazura and Digurv find an unexpected ally in Acqua. Takitsubo receives some welcome news from Elizalina. Kamijo and Lessar attempt to infiltrate Fiamma's base.

After dealing with the sorcerers at the Russian airbase, Accelerator has a Misaka clone skydive down to confront him. Vento challenges Fiamma while Kamijo and the others watch on. Hamazura gets some disturbing news from Digurv.

Técpatl and Unabara square off in Shiokishi's chambers, while Accelerator and Sugitani face each other in the hallway outside. Kinuhata discovers the true reason for the current assault against herself, Takitsubo, and Hamazura.

Accelerator and the other members of GROUP are assigned to eliminate the members of Spark Signal, a terrorist group which has taken hostages. Hamazura and Kinuhata find themselves on the run when they defy the city's higher-ups.

Acqua and Knight Leader continue their fateful showdown in the forest. Princess Carissa reveals a devastating new technique using Curtana Original. When Kamijo and Index's lives are endangered, an unexpected ally comes to their rescue.

After being escorted to London, Kamijo and Index have an audience with the queen and three princesses to discuss the threats facing Britain. Upon dividing into separate teams, Kamijo assists with tracking down the members of New Light.

Kanzaki battles Acqua under Academy City, but finds herself overpowered by his might. Mikoto runs into Kamijo after he sneaks out of his hospital room. Kanzaki works with the Amakusa Church members to find a way to beat Acqua.

Itsuwa reveals to Tōma she has come to Academy City as his bodyguard to protect him from Acqua, who is now targeting him for ruining God's Right Seat plans. While Itsuwa's Amakusa comrades watch from afar and plan to have she and Touma to get close and be a couple, Mikoto is still dealing with the revelation of Tōma's amnesia. Tōma brings Itsuwa to his home, where Index accidentally destroys the bathroom, which Itsuwa decides to bring Tōma and Index to a spa located in 22th District's underground city. After an awkward meeting between Itsuwa, Index and Mikoto in the spa, Tōma and Itsuwa takes a walk at a park. However, Acqua appears, having defeated the rest of the Amakusas, demands Tōma hand over his right arm which contains Imagine Breaker. Tōma and Itsuwa tries to fight back but are unable to hit him due to Acqua's Saint powers. After beating Tōma to a pulp, Acqua gives him one more day before he gets his right arm while Itsuwa feels guilty for failing her mission.

While Kazari takes a lost Last Order home, Accelerator arrives at his location and faces Saraku, a teleporter of MEMBER and defeats him after realizing Saraku can only teleport behind his opponents. Elsewhere, MEMBER's leader "The Professor" confronts Teitoku only to be killed by the latter after using his power, Dark Matter. Meanwhile, BLOCK starts their real goal, to shut down the city's surveillance system and help 5000 mercenaries invade the city. However, one of their members is actually Etzali in disguise, who alerts the city's drone helicopters to head to their location and stop the mercenaries. Despite their heavy loses, the remaining BLOCK members, Saku Tatsuhiko and Megumi Teshio, continues their next part of the plan, bringing the mercenaries to Academy City's detention facility and kidnap Awaki's gang to use as leverage to make her help them enter the Windowless building and kill Aleister. GROUP heads to the detention facility where Accelerator stays back to hold off the remaining mercenaries while Etzali faces off against Xochitl, a MEMBER agent and his colleague from the Aztec organization who has come to Academy City to kill Etzali for treason. Tsuchimikado and Awaki confronts Saku and Megumi trying to free Awaki's gang but Megumi kills Saku for endangering the hostages and decides to forcefully get the information from Awaki instead. Despite Megumi knocking out Tsuchimikado, Awaki is able to defeat Megumi after getting over her trauma of teleporting herself. With the hostages safe and Etzali saving Xochitl's life from the grimoire she was using, GROUP heads back home. However, Teitoku arrives at ITEM's apartment after torturing Frenda for information.

Tsuchimikado appears and joins forces with Tōma and Itsuwa against Terra, who flees when a platoon of powered suits sent by Academy City interfere with their fight. Tsuchimikado then stays behind to stop the suits while Tōma and Itsuwa chase after Terra at the Palais des Papes. Once there, Tōma contacts Mikoto by phone and learns from her that according to the media, Academy City launched an attack on Avignon in retaliation against a plan to attack it, but their conversation is cut short when Terra, having the C Document in his hands, attacks him. During their fight, Terra realizes that Tōma still has not attained the full power of Imagine Breaker because he lost his memory, but nevertheless, Tōma takes advantage of a weakness in Terra's abilities to defeat him and destroy the C Document. Just as Tōma is about to inquire Terra about what he knows about Imagine Breaker, a squad of stealth bombers led by Accelerator attack the palace, allowing Terra to escape. However, at St. Peter's Basilica, Terra is killed for involving civilians in the conflict by Acqua of the Back who decides to take the war against Academy City personally after Terra and Vento's failures.

Since the September 30 attack on Academy City by The Right Seat of God's Vento of the Front, tensions grows between the Catholic Church and Academy City, with the latter's tightening their security. Tōma has an unlucky day where he gets bitten by a hungry Index, hit by a ball on the head by Seiri, accidentally sees his teacher Suama Oyafune removing her skirt and gets attacked by Mikoto after the latter discovers a selfie of him and her mother Misuzu in his phone. As he heads home, Tōma is forced to follow an old woman named Monaka Oyafune, Suama's mother, to an empty park. Monaka reveals to Tōma that she is one of Academy City's Board of Directors and fears the upcoming war and wants him to investigate whether the recent world wide protest against Academy City are really the work of the Catholic Church. Tsuchimikado appears and shoots Monaka, which the latter explains she ordered the former to shoot her to protect her family and satisfy the rest of the Pro-War Board of Directors for talking with Tōma behind their backs. Agreeing to work with her, Tōma follows Tsuchimikado as they head to Avignon, France via a supersonic jet.