Academy City Invasion Arc

The Academy Invasion Arc is a major story arc in Toaru Majutsu no Index. It features a series interrelated events occurring in Academy City during Vento of the Front's attempt to search and kill Kamijou Touma, who has now become an enemy of God and the Roman Catholic Church; and Accelerator's struggle to protect Last Order, as he fights against his former mentor Kihara Amata.

In-universe it is called the 0930 Incident, an event that would influence several other events and story arcs to come later in the series, and would be the primary trigger for the final arc of the Toaru Majutsu no Index series before New Testament. This is most notably due to the now apparent hostility between the two sides after the events of the arc as well as the acknowledgment of the existence of "magic", and the ever increasing presence of Kamijou Touma and his Imagine Breaker in magic side affairs.

Investigation of Kamijou Touma
After several incidents of having their plans thwarted such as the Book of the Law incident, the Croce di Pietro fiasco, and most recently the Adriatic sea disaster, as well as steadily having their strength decrease, the Roman Catholic Church finally decided to investigate one common factor in all of these events, Kamijou Touma. After the destruction of La Regina del Mare Adriatico, an investigation was set-up by the Pope under the command of Vento of the Front to investigate if Kamijou Touma is an enemy of God (and by default the Roman Catholic Church), and if so have him executed.

The document for authorization of the investigation was handed to the Pope on September 26 of the timeline, and was later approved shortly; the investigation lasted for five days and confirmed Kamijou Touma as an enemy of God.

Invasion plan
The Roman Catholic Church's plan to invade Academy City is to have Vento of the Front cripple the city's defenses and populace through the use of Divine Punishment, at which point the support units outside would use Crested Ibis stakes to stab the unconscious masses, as a way to mitigate losing scores of their forces if they try to invade the city head-on. This is due to the limited number of forces the church deployed, as such they are using Vento of the Front's Divine Punishment at full advantage.

However, the invasion plan in itself is just an accessory to Vento of the Front's true mission, which is to kill Kamijou Touma which takes priority over other targets such as Index and Aleister Crowley and would even destroy Academy City itself just to get it done.

Before the invasion
Accelerator and Last Order is finally released from a certain hospital after an entire month of being confined. Here, they move into the Yomikawa Residence im the Family Side after Yomikawa Aiho becomes their guardian. Meanwhile, Touma is forced to accompany Misaka Mikoto on her Penalty Game that they agreed upon during the events of the Daihasei Festival, though with notable disturbances in excursions with him such as Touma's unwillingness and Shirai Kuroko's ineccessant invasion of their privacy.