Due to her parents' job transfers, high school student Makoto moves in with her father's friend's family for two years. She is determined to stay strong and independent, but her plans are immediately upended when she discovers that the family includes Kanna, the most popular boy at her new school. Makoto already has a reason to hate him: he recently dumped her close friend Tamako without any explanation. To make matters worse, Kanna is a relentless prankster who seems to enjoy teasing her, pulling her hair, and calling her stupid. Despite his cold and arrogant exterior, he is also surprisingly protective and physically affectionate, often kissing her without warning. Forced to share a roof, Makoto and Kanna clash constantly, but beneath the bickering, an undeniable attraction begins to form.

The story follows their rocky journey from mutual irritation to reluctant intimacy. Makoto is a clumsy, emotionally open girl who longs for a normal romance, while Kanna is a guarded, moody teenager who refuses to verbalize his feelings. Their living arrangement forces them to see each other's vulnerable sides, but Kanna's refusal to clearly define their relationship leaves Makoto confused and frustrated. Meanwhile, friends and rivals complicate the situation: Makoto's bubbly best friend Tamako gets a new boyfriend, causing Makoto to feel left behind; Kanna's friend Kenken provides comic relief; and two romantic rivals emerge—Asakura (often called Ayase in some translations), a manipulative girl who pursues Kanna, and Minami, a kind classmate who develops feelings for Makoto. These characters test the couple's bond, leading to jealousy, misunderstandings, and emotional confrontations.

Key narrative arcs include Makoto and Kanna's first kiss under accidental circumstances, their struggles to admit they are essentially dating without a formal confession, Kanna's possessive and passive-aggressive reactions to Makoto's interactions with other boys, a period of separation when Makoto temporarily moves out, and a final reconciliation where Kanna finally confesses his love. The story concludes with the couple overcoming their communication problems and committing to a genuine relationship, with extra chapters showing their life after high school. The manga emphasizes the theme that love can begin even under the worst first impressions, and that true feelings require patience and honest words.