New Year's Eve Arc

The New Year's Eve Arc is the sixth story arc of Souyaku Toaru Majutsu no Index, covered in .

On December 31st, with his home situation dire, Kamijou Touma decides he must find part-time work in order to obtain enough money to survive until January 4th, and following an invitation by Kumokawa Seria, ventures outside of Academy City and into Shibuya. However, his previous adventure with Alice and the change it caused in her, has made him a target of her fellow Transcendents in the Bridge Builders Cabal, the group split between how to deal with the matter. On the side wishing to eliminate him, the witch goddess Aradia attempts to take Touma's life, with the boy only surviving her initial attack due to the intervention of the Bologna Succubus, on the side wishing to keep him alive for now.

Golden Dawn
Prior to the founding of the Golden Dawn, founders Samuel Liddell MacGregor Mathers and William Wynn Westcott were mentored by a powerful magician known as Anna Kingsford. She died shortly before the cabal's founding, with Westcott believed to have used her as a basis for the figure in the Sprengel Letters, key in the founding of the cabal. Regardless of whether the Rosicrucian temple chief Anna Sprengel was an invention or actually existed prior to the alleged correspondence, this association formed a magical connection between the two Annas, one which would leave Sprengel at a disadvantage against Kingsford.

Anna Kingsford's death meant that Aleister Crowley would not experience her teachings, with the already pessimistic magician instead experiencing the more self-centered mentoring of her pupils and the conflict between them that divided the cabal, which Aleister would eventually turn against and exploit to destroy them in the Battle of Blythe Road. Afterwards, Aleister would establish his own systems of Thelema and Magick, and among other things, start a story associating Lewis Carroll's  with Kabbalah, as well as possibly interacting with the creator of Wicca, Gerald Gardner.

In the present, following the chaos caused by the restored Anna Sprengel, Aleister Crowley sought Anna Kingsford to use against the Rosicrucian, with her body amongst the collection of a nameless group of wandering treasure keepers who preserve notable individuals (including the remains holding the previous Imagine Breaker which the Golden Dawn stole, and nearly added Aleister himself to their collection after his 'death' in 1947). Following the events on December 29th, Aleister located Anna Kingsford's body, hidden in the kitchen of a restaurant in the Miyashita Ark, a shopping mall recently opened in Shibuya (with the treasure keepers possibly behind it).

Witches
Witches have existed since ancient times, said to be forest-dwelling priestesses of the night and the moon. Following the rise of Christianity, they were subjected to slander by the church and purges known as the. Although the large-scale witch hunts declined due to criticism, there are still cases of persecution in the present day and for some, the witch hunts have never truly ended.

In 1954, magical researcher announced and released a modern system of witchcraft known as Wicca, a supposed reproduction of the practices and religion of ancient witches from before Christianity based on his own studies. Alongside concepts such as the Book of Shadows and the Rule of Three, central to Wicca is the concept of the goddess of all witches, Aradia. The grimoire Aradia, or the Gospel of the Witches presents a report on Aradia supposedly conveyed to the author by an Italian witch, which Gardner believed and incorporated into his system, though given no mythology has a goddess of that name and her supposed lineage given in the story (daughter of and ), many have considered it likely the witch made it up to match what the author wanted to hear.

Regardless, a Transcendent witch bearing the name and role of Aradia does exist, and seeks to protect witches even in the present day. One recent failure that affected her was the death of an old woman living alone in a forest who had been made the scapegoat for an illness and had her home set on fire, who had urged her to save the next one before dying in Aradia's arms.

Bridge Builders Cabal
The Bridge Builders Cabal was formed by powerful magicians, known as Transcendents, each capable of rivalling the conventional magic side on their own. All of them seek to make the world a better place, but given the limitations of the world, their own immense powers and their differing individual reasons, they gathered together in order to avoid conflict and determine the best way to achieve their collective goal. One Transcendent among them, a young girl known as Alice Anotherbible, possessed a childish nature which when coupled with her unique power, could jeopardize their plans as well as accomplishing them, leading the others to fear her as a Tyrant and appease her whims.

However, their newest member, Anna Sprengel, incited Alice into coming into contact with Kamijou Touma and their subsequent adventure resulted in a change in the girl which put the Bridge Builders Cabal's plans at risk, resulting in the group becoming split over how to approach the issue. The Killers sought to immediately eliminate Touma, in the hopes that removing the root cause of the change would solve the problem with Alice as soon as possible, while the Rescuers sought to keep him alive to the time being and monitor the precarious situation, recognizing that killing him might not resolve and might even worsen their problems. Aradia was on the side of the Killers, while the Bologna Succubus and Good Old Mary were on the side of the Rescuers, with the instigating Anna Sprengel not picking a side.