Sakuta Azusagawa, a second-year high school student, encounters Mai Sakurajima, a famous actress, in a library wearing a bunny suit, and discovers that no one else there is able to see her, even when she stands right in front of them.

Sakuta promises to meet Mai for a date, but an incident with a lost girl waylays him; Mai makes a decision about her acting career, but in doing so discovers how far the effects of her Adolescense Syndrome have spread.

Everyone except Sakuta and Futaba lose their memories of Mai; Sakuta goes to desperate lengths to stay awake through three days of exams after Futaba deduces the cause of the memory loss.

Sakuta's elation at Mai's agreement to date him collapses when he wakes up to find himself reliving the fateful day over and over; at Futaba's suggestion, Sakuta searches the school for the student causing the repetition.

A boy asks Tomoe out on a date, but she wants to refuse because one of her friends happens to have a crush on him; Tomoe comes up with an excuse, but it involves reinforcing the existing rumor that Sakuta is her boyfriend.

With the first term ending, Sakuta and Tomoe come to the final day of their pretend relationship, but after their civil "break-up," an unexpected relapse of Adolescence Syndrome leads Sakuta to suspect Tomoe's problem still isn't resolved.