On the first day of high school, Hiro Furuya arrives late, missing the opening ceremony but immediately crossing paths with the beautiful and popular senior, Himari Asaki. He falls for her at first sight and begins a relentless campaign of daily confessions, only to be rejected each time, eventually racking up fifteen failures. Unknown to him, Himari suffers from androphobia, a fear of men that makes her studiously avoid his advances, though a connection through Hiro's sister begins to build an unexpected bridge between them. Circling within the same social circle is Hiro's friend, Akechi, a meticulous student who keeps a detailed notebook compiling intelligence and secrets on all the girls at school. His clinical curiosity becomes complicated when he sets his sights on an extremely quiet and shy classmate, as his professional interest in her mysteries begins to morph into genuine personal feeling.

Instead of following a single pair, the narrative shifts its focus regularly, allowing the perspective to rotate among a large cast of approximately twelve main characters who are all connected as either classmates, siblings, or friends. The story is set within the familiar environment of a Japanese high school, with periodic excursions during summer or other seasonal breaks. As the series progresses, it develops the romantic lives of roughly six distinct couples, each facing their own specific obstacles. One early arc follows a love triangle where a girl secretly harbors feelings for a popular boy who is viewed as belonging to someone else, while another deals with the hesitant steps toward a new start after a painful misunderstanding. The problems range from childhood traumas and past heartbreaks to unrequited love and the fear of ruining a friendship by admitting deeper feelings. Confessions are often dramatic, staged at school rooftops or during sunset by the sea, and involve emotional outbursts and passionate speeches from supportive friends who push the hesitant protagonists forward.

As the chapters progress, the volume includes side stories that continue to tie up loose ends, such as The Secret Love My Friend Doesnt Know About, which explores hidden affections within the established friend group, and the multi-part Welcome Home, which provides a concluding epilogue for the wider ensemble. The series resolves its various love polygons, ensuring that by the final chapters, the majority of the interconnected classmates have found a partner and achieved a stable relationship, often leading to a heartwarming conclusion that shows where the characters end up after the drama of their younger years has settled. A separate but related series exists under a similar title featuring completely different characters and themes.