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.