Second-year high school student Hibiki Shimada has always been an avid archery enthusiast, but she has yet to experience the thrill of romantic love. Despite this, she has formed a close friendship with Megumi Chigusa and Kosuke Kawai, two love-struck teens who boldly express their affections for their teachers, Masato Sekiya and Sachiko Nakajima, respectively.
An unexpected twist unfolds when Hibiki accidentally sends a love letter meant for Chigusa to Kosaku Ito, the world history teacher whom she secretly adores. In her attempt to retrieve the letter, her admiration for Ito deepens as she witnesses his unexpected kindness. Known for his stern demeanor, Ito surprises Hibiki by taking her to the hospital after she has an accident in front of his car, assisting her with assignments outside of school hours, and offering her rides home.
Meanwhile, Chigusa takes a step back from her pursuit of Sekiya upon realizing that his heart belongs to Nakajima. However, it comes to light that Nakajima herself has feelings for Ito, a fact that Hibiki and Kosuke discover when they overhear her confession to him, which ultimately results in rejection. After all this emotional turmoil, Hibiki decides to express her love to Ito before their finals. She proposes an unusual arrangement: if she achieves over 90 points on the history test, she believes it would mean he is meant to reciprocate her feelings.
Throughout her journey, Hibiki faces discouragement from both Nakajima and Ito himself. However, with a motivational boost from Yusuke Fujioka, an archery student from a nearby school, she gathers the determination to succeed. When the test results are eventually revealed, Hibiki expresses her love for Ito at the cultural festival, dressed in a wedding gown costume, declaring her everlasting love. To her delight, Ito embraces her and shares a kiss.
The aftermath of their kiss sends shockwaves through the school, resulting in Hibiki’s suspension and Ito facing disciplinary measures. When they cross paths again, Ito takes it upon himself to discourage Hibiki further from a potential relationship. On her way home, feeling dejected, Hibiki finds solace in Fujioka’s confession of feelings for her. The day following the disciplinary meeting, students learn that Ito will be transferring to another school.
As Hibiki remains suspended, she is unaware of this news until Chigusa rushes to her home, urging her to meet Ito one last time. During an emotional confrontation, Kosuke expresses his anger at Ito’s decision to abandon Hibiki, questioning the sincerity of his earlier vows. Fueled by encouragement, both Hibiki and Ito race to meet and share a heartfelt confession of love, with Ito asking Hibiki to wait until she comes of age for them to start their relationship properly.
Fast forward a year and a half later, Hibiki is on the brink of graduation. Chigusa has found a new romance with an underclassman, while Kosuke continues to pursue Nakajima. On the day of her graduation, as Hibiki leaves the school grounds for the last time, she is greeted by Ito, who congratulates her and inquires about her wishes. Hibiki expresses her simple desire to hold hands with him. The concluding scene of their story captures a tender moment where the two hold hands and share their first kiss as a couple.
