The story begins with Kashiwagi Kouta, a quiet and unassuming high school second-year, recounting the painful memory of his childhood friend, Kirishima Kana. In middle school, Kana, who had become stylish and popular, cruelly told Kouta to never speak to her again, calling him an embarrassment. This deeply traumatized Kouta, leading to three years of complete estrangement. His peaceful school life is shattered when he discovers Kana is not only in his new class but seated directly in front of him. Kouta, still hurt and believing Kana despises him, resolves to avoid her at all costs, relying on his outgoing best friend, Momoyama Masaki, as his escape. Masaki, a fellow "go-home club" member who loves anime and light novels, is Kouta's only close friend at school and provides him with much-needed support and distraction.
Kouta's paranoia intensifies when Kana and her friend, Igarashi Iori, unexpectedly appear at the same seafood bowl restaurant where Kouta and Masaki are having lunch. Kana's glances make Kouta feel stalked and uncomfortable, a feeling that persists when he notices her and Iori seemingly following him home from school. Kouta interprets these actions as Kana trying to find his weaknesses or simply being annoyed by his presence.
Meanwhile, Kana is consumed by regret and a burgeoning love for Kouta. She realizes she pushed away a significant person in her life and now desperately wants to reconcile. Her best friend, Iori, a sensible and supportive classmate, notices Kana's constant glances at Kouta and encourages her to act on her feelings. Kana's initial attempt to speak to Kouta during lunch fails spectacularly; Kouta, startled and wary, addresses her formally as "Kirishima-san" and quickly flees, mistakenly thinking she wanted his seat. Devastated, Kana breaks down, lamenting that Kouta no longer calls her by her given name.
Iori, having overheard Kouta's conversation with Masaki, realizes Kana's interpretation of Kouta's feelings is flawed. Kouta, while remembering the past hurt, doesn't hate Kana; he simply believes she hates him and that reconciliation is impossible. Iori sternly confronts Kana, pointing out her self-pity and self-centeredness. She makes Kana realize that her primary motivation for apologizing should be to atone for the pain she caused Kouta, not merely to fulfill her own desire for reconciliation or to rekindle their relationship. This intervention is a turning point for Kana, who finally understands the depth of Kouta's hurt and the true meaning of a sincere apology.
With a newfound resolve, Kana, guided by Iori, decides to approach Kouta properly. Recognizing Kouta's avoidance, they devise a plan to involve their mothers, who are still friendly, to create a structured opportunity for Kana to apologize to Kouta during the upcoming Golden Week. Kouta, still oblivious to Kana's true intentions and convinced she dislikes him, remains wary and anxious about their continued interactions.