Season 1: The Breaking of the Shell: Sawako enters high school ostracized as "Sadako." Kazehaya encourages her to participate in the Courage Test, helping her connect with Ayane and Chizuru. When malicious rumors about Ayane and Chizuru are blamed on Sawako, she confronts bullies in a school bathroom, and the three girls form an unbreakable bond. Later, popular girl Kurumi attempts to manipulate Sawako, but Sawako stands firm in her feelings for Kazehaya. Kazehaya rejects Kurumi, and by New Year's Eve, Sawako and Kazehaya share a deep mutual attraction.
Season 2: The Agony of Misunderstanding & The Confession: New classmate Kento Miura misleads Sawako into believing Kazehaya is out of her league and that confessing will burden him. Sawako fails to deliver her Valentine's chocolates, causing Kazehaya to feel rejected. During the School Festival, Sawako realizes silence is hurting Kazehaya, bursts into his classroom, and passionately confesses. Kazehaya reciprocates by the festival bonfire, and they become a couple.
Season 3 & Finale: Navigating Reality & The Future: The couple works through the awkward realities of physical boundaries and Kazehaya's fear of his own desires. Concurrently, Chizuru confronts Ryū's steadfast romantic love as he prepares for college baseball, while Ayane ends a hollow romance with Kento to learn self-love. The anime concludes on an open, hopeful note with the circle of friends facing graduation united in love and trust.