The Christmas Eve Arc is the first story arc of Souyaku Toaru Majutsu no Index, covered in Souyaku Toaru Majutsu no Index Volume 1.
On December 24th, after having his remedial lessons scuppered, Kamijou Touma decides to spend his Christmas Eve in the city, together with Index and Misaka Mikoto, who has escaped from Tokiwadai's strict oversight. Meanwhile, Academy City's new Board Chairman Accelerator prepares to initiate Operation Handcuffs - the operation to eliminate the city's dark side, a move which is not without resistance. At the same time, another threat starts to creep into the city.[1]