The story takes place from December 17 until December 24, a month after the cultural festival.
On December 17, everything is normal. The SOS Brigade, led by Haruhi Suzumiya, plans to have a nabe party for Christmas. However on December 18, Kyon arrives at school to find everything has changed. Haruhi is missing, and Ryoko Asakura, who had previously been deleted by Yuki Nagato, is a normal student. Yuki is an ordinary human, and Mikuru Asahina does not recognize him. Only Kyon is aware that everything is different. The only clue is a bookmark left by the alien version of Yuki, which leads Kyon on a quest back in time, where he interacts with the storyline from "Bamboo Leaf Rhapsody", trying to sort out the mystery and return to his own time line.
