With only 8 days to Christmas, the SOS Corps, under the call of Haruhi Suzumiya, unexpectedly planned a Christmas carnival party. But on the morning of December 18, Kyon found that the world around him had changed a little. Class 9 of Year 1 disappeared, and Senior Asahina treated them as passers-by. Even the long-dead Asakura replaced Haruhi Suzumiya and sat behind Kyon, while Haruhi seemed to have evaporated from the face of the earth and no one knew about it. When he rushed to the classroom of the SOS Corps, he only saw Yuki Nagato sitting alone in the corner reading a book. The always calm and cold Nagato Okami had also become a timid and shy good girl. From the clues left by Nagato the day before, Kyon judged that the world seemed to have been reorganized by someone. At this time, Kyon, holding the key to connect two completely different worlds, faced a major choice...