On the 29th of May, Sakuta Azusagawa wakes up from a hazy dream and finds a journal which describes how, on the 6th of May, he met a senior from school wearing a bunny girl costume in the public library. Her name, however, has been erased from the journal. Mai Sakurajima, a teen celebrity, had gone to the Fujisawa Library that day to test if people there could still see her. While on hiatus, she enters school but it was midway through after the students have already formed their social circles...