On a chilly winter day, Kyon anticipates another adventure with his SOS Brigade comrades at school. To his astonishment, he realizes a drastic transformation: Haruhi Suzumiya and Itsuki Koizumi are missing, Mikuru Asahina fails to recognize him, Yuki Nagato appears human, and Ryouko Asakura resurfaces mysteriously. Despite his familiarity with the supernatural, Kyon is perturbed by these unsettling changes, prompting him to launch a solo investigation. As the sole bearer of the past reality, Kyon faces a daunting dilemma: embrace the ordinary life he craves or seek a method to rewind time and restore the chaotic yet beloved world he once knew.