Kanoko Naedoko has always been an observer of human nature rather than a participant in the social dramas unfolding around her. A quiet and sharp-witted middle school student who constantly transfers schools due to her parents' work, she keeps herself detached by documenting her classmates' behaviors and secrets in a notebook, finding more entertainment in analyzing their interactions than forming bonds of her own. This self-imposed solitude becomes complicated when she attracts the attention of Haru Tsubaki, a popular and aloof boy intrigued by her refusal to play social games. Over several transfers, Tsubaki continues to appear at her new schools, offering help while harboring romantic feelings that the oblivious Kanoko misinterprets as platonic persistence. Along the way, she unwillingly accumulates genuine friends including the sweet but bullied Momoka Hanai and the earnest Touta Natsukusa, slowly transitioning from a disengaged observer to someone who solves the romantic problems of those around her while remaining blind to her own love life.

The story continues in high school with Koi da no Ai da no, where Kanoko makes a rare agreement with her parents to live in a dormitory so she can remain at a single school for the first time. Determined to reinvent her image, she instead finds herself recruited into the newspaper club due to her unparalleled information-gathering abilities. She quickly discovers that each club at the school operates under different budgets and social standings, leading her to engage in subtle information warfare to raise the newspaper club's position while untangling the romantic troubles of her peers. The narrative blends episodic problem-solving with ongoing character development, as Kanoko navigates friendship dynamics, school politics, and her deepening connections with recurring figures from her past including her devoted friend Momoka, the teasing Tsubaki, and new acquaintances like the aspiring artist Mitsue Aida and newspaper club member Kyoko Shinonome.

The sequel Koi da no Ai da no ~Kimi wa Boku no Taiyō da~ picks up further along Kanoko's journey, maintaining her distinctive personality as a brutally honest protagonist who reads others with precision but remains incapable of recognizing romantic interest directed at herself. Throughout the series, which spans from her turbulent middle school years through high school, Kanoko encounters a series of memorable characters including Marine Suitengu, a manipulative classmate who pretends to be humble, and Sachiko Kinokodani, whose elaborate revenge plot against a romantic rival Kanoko observes more than participates in. The narrative arcs typically involve Kanoko using her observational skills to resolve interpersonal conflicts and romantic misunderstandings for others, while Tsubaki patiently waits for her to finally notice his feelings. Her eventual romantic awakening and the development of a relationship with Tsubaki form the emotional core of the longer storyline, with the series concluding with implications of their future together beyond high school. The setting shifts across multiple school environments, from various middle schools to a single high school dormitory, creating a framework where Kanoko's growth from isolated observer to engaged participant unfolds gradually across the interconnected stories.