Christmas

Christmas (クリスマス) is an annual holiday, primarily observed on December 25th. It is a Christian celebration, commemorating the birth of the Son of God, but the festival is also celebrated by many others across the world.

Santa Claus
Santa Claus (サンタクロース) is a figure commonly associated with the modern-day Christmas. He is said to be a jolly old man in a red suit who secretly delivers presents for good children while they are sleeping on Christmas Eve, riding through the skies on a sleigh drawn by reindeer. The character of Santa Claus is derived from several figures, including.

According to Leivinia Birdway, there is an organization known as the Nicholas Foundation (ニコラウス財団), presumably a secret Magic Side organization related to Santa Claus, which she briefly mentioned when she mistook the child Fremea Seivelun's comment that she knows Santa Claus exists as a deliberate reference to the organization. It is unknown whether the organization has an actual Santa Claus as Leivinia Birdway's reaction implies that the character Santa Claus exists. No other mention of the organization has been made since.

Daihasei Festival Arc
When the Night Parade began, the way the International Airport in School District 23 started to shine was compared to the decorative lights on a Christmas tree.

Acqua of the Back Arc
Even though it was September, Christmas cards from all over England were arriving at Lambeth Palace. It was briefly mentioned that the Archbishop would dress up as Santa Claus and visit forty-three children's welfare facilities.

Homecoming Arc
Leivinia Birdway mentioned the Nicholas Foundation when she mistook Fremea Seivelun's comment that she knows Santa Claus exists as a deliberate reference to the organization.

Coronzon Arc
It is briefly mentioned that the Vatican runs a dedicated freight train to deliver Christmas cards sent from all over the world.

Christmas Day Arc
On Christmas Day, incidents were occurring around the world due to the magical knowledge distributed online by R&C Occultics (including the self-destruction of Anna Sprengel's collaborators). The effects were particularly severe in Academy City, where hospitals were overwhelmed with casualties, suffering injuries from the rejection reaction from espers attempting magic (with a Christmas good luck charm ironically prominent among the causes).