First-year high school student Yuu Koito Misato Kawauchi unexpectedly receives a confession from a middle school classmate. Feeling that she does not understand love, she turns him down. She later sees second-year student council member Touko Nanami Moeka Koizumi turning down a confession, and becomes convinced that Touko feels similarly about romance. She approaches Touko and the two begin to bond, before Touko suddenly confesses feelings for Yuu, surprising her. Although Yuu does not feel capable of reciprocating, Touko is not bothered by this and says she would be very happy if Yuu were to not return her feelings.
Touko runs for the position of student council president and asks Yuu to be her campaign manager. To the dismay of Touko's best friend Sayaka Saeki, Karin Isobe accepts the role. Touko expresses that she feels emotionally reliant on Yuu, as she is the only one to whom Touko can be vulnerable. Yuu decides to join the student council in order to support Touko, who ultimately wins the election.
As president, Touko plans to revive the student council play, which has not been performed in seven years. Yuu is against the idea, and chooses not to suggest her novelist friend Koyomi Kanou when the other members ask who could write it. Sayaka tells Yuu to solicit Koyomi's involvement, and to look into the student council president of seven years ago. Yuu subsequently learns that Touko's older sister Mio was the student council president at that time, and had been producing a play, but was killed in a traffic accident before its premiere. Yuu realizes that Touko is emulating her sister and wants to produce the play in her place. She tries to convince Touko that this is unnecessary, but Touko coldly refuses.
Koyomi finishes the first draft of the play. The narrative follows an amnesiac girl who must choose which person's view of her is her true self, with the original ending involving the girl choosing her lover's view. When the student council holds a study camp to practice for the play, actor Tomoyuki Ichigaya, a former classmate of Mio's, is brought in to help. From him, Touko learns that Mio was a very different person than who she is now, leaving her conflicted. Concerned, Yuu has Koyomi change the ending to have the protagonist choose to be herself instead of conforming to a specific person's view, believing that this will help Touko come to terms with herself. When the play is performed at the cultural festival, its narrative and Touko's performance are acclaimed by the audience, and the manager of a local theater troupe approaches Touko, asking her to join them and become an actress. She initially declines, but eventually reconsiders and accepts.
Touko thanks Yuu for her support and reiterates her wish for Yuu to stay with her as she is. However, Yuu has developed feelings for Touko, and abruptly confesses her love. She misinterprets Touko's shocked response as rejection and runs away, causing Touko to realize that she has been overly imposing. Meanwhile, Sayaka speaks with café owner Miyako Kodama, in whom she confides her own romantic feelings for Touko. When the second-years take a class trip to Kyoto, Sayaka formally confesses to Touko. Touko turns Sayaka down, acknowledging her love for Yuu. Although dejected, Sayaka accepts this. Elsewhere, Yuu realizes that she is running away from her problems. The two reconcile and Yuu finally openly reciprocates Touko's feelings.
Over time, Yuu and Touko become more emotionally and physically intimate with each other. This culminates when they go bowling together, with the agreement that whoever wins gets to make a request of the other. Yuu wins and asks to sleep over at Touko's house. Touko agrees, confessing she had wanted to arrange that as well. They spend the evening at Touko's parents' condo, where they have sex.
Three years later, Yuu and Touko have graduated high school, enrolled in college, and are now wearing rings on their fingers. They reunite with the former student council members to attend the cultural festival at their old high school. As Yuu and Touko reminisce about how their relationship started and reflect on their new lives as adults, they walk off into the night.
