On a cold December day, Kyon arrives at school prepared for another outing with his fellow SOS Brigade members. However, much to his surprise, he discovers that almost everything has changed completely: Haruhi Suzumiya and Itsuki Koizumi are nowhere to be found; Mikuru Asahina does not recognize him at all; Yuki Nagato is a regular human; and Ryouko Asakura has mysteriously returned. Although he is no stranger to the supernatural, Kyon is disturbed by this odd turn of events and decides to investigate on his own. Finding himself to be the only person that is aware of the previous reality, Kyon is now faced with a difficult choice: to finally live the normal life he has always wanted, or uncover a way to turn back the hands of time and restore his chaotic yet familiar world. It is mid-December, and SOS Brigade chief Suzumiya Haruhi announces that the brigade is going to hold a Christmas party in their clubroom, with Japanese hotpot for dinner. The brigade members Kyon, Nagato Yuki,Asahina Mikuru and Koizumi Itsuki start preparing everything for the party, such as costumes and decorations. But a couple of days later, Kyon arrives at school only to find that Haruhi is missing. Not only that, but Mikuru claims she has never known Kyon before, Koizumi is also missing, and Yuki has become the sole member of the literature club. The SOS Brigade seems to have never existed, nor has Suzumiya Haruhi. No one in the school has ever heard about her... except for Kyon.Now it is up to him to travel back through time to find Haruhi and correct the temporal anomaly.