A new visitor appears with Mikuru to enlist the SOS Brigade to find her missing boyfriend, who happens to be the computer club president that Haruhi extorted. As they go on the hunt for him, a closed space begins to form. Can they save him in time?

Haruhi is visibly bored and is not her usual energetic self. Ryoko Asakura, the class president, is concerned and asks Kyon to help her. Kyon later finds a mysterious letter in his locker, which directs to come to a classroom, where Ryoko confronts him. Revealed to also be an alien, Ryoko attempts to kill Kyon in order to provoke a reaction from Haruhi, but is stopped by Yuki. Later, Kyon meets Mikuru's older self that had traveled from the future, who reveals that Snow White is the clue essential to his future. Ryoko was reported to never have transferred into the high school, much to Haruhi's suspicion.

On the day of the school's cultural festival, the members of the SOS Brigade are involved in different activities. Mikuru and her class open a fried noodles café, Yuki attempts fortune telling, and Itsuki is in a play. Kyon attempts to enjoy a normal day. Kyon goes to the auditorium, where bands are playing for the audience, and falls asleep. When he awakens, he sees Haruhi walking on stage in a bunny girl costume with a guitar hanging from her shoulders.

The previous time loop continues for the 15,513th time. This time, Kyon mentally senses an even greater familiarity with events and places from previous cycles. Once again, none of the Brigade members can devise anything to stop the cycle from repeating. On their final meeting in the restaurant, Kyon tries to call out after Haruhi but fails to do anything as visions of the loop's events flash in his mind. As Kyon regains his senses, Haruhi has left. As the last day of vacation arrives, Kyon, resigned to the loop repeating itself, goes to bed without finishing his summer homework.

The previous time loop continues for the 15,524th time. Kyon goes to bed without finishing his summer homework once again.

As the SOS Brigade shoot more of their film, Haruhi tries to give Mikuru another contact, ergo another superpower. Yuki quickly takes action and injects her with more nanomachines before any damage could be done. Despite the weird phenomena Haruhi's film is causing, Itsuki suggests it is better than more closed spaces being opened up. However, when Kyon discovers Haruhi arranged for Mikuru to be drugged for a kiss scene with Itsuki, he gets furious at her shabby treatment of Mikuru and almost hits her, forcing Itsuki to hold him back. This causes Haruhi to become depressed, having always thought Kyon would support her. Kyon, reluctantly learning something from Taniguchi, later apologizes to Haruhi and filming resumes. However, he seems to have inadvertently encouraged Haruhi even more, making cherry blossoms grow out of season.