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
The International Airport in School District 23 starts to shine like the decorative lights on a Christmas tree.

Acqua of the Back Arc
Even though it is September, Christmas cards from the all over England is arrived in the Lambeth Palace. It is briefly mentioned that the Archbishop will 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.