"Osananajimi ga Zettai ni Makenai Love Come" centers on the romantic rivalry between two childhood friends, Shuro Kurokami and Marin Nikaido, who have known each other since elementary school. Shuro is a reserved and academically gifted student, while Marin is outgoing, athletic, and fiercely competitive. Their relationship is defined by a long-standing rivalry, with Marin constantly challenging Shuro to prove her superiority in various contests, from academics to sports. Despite their constant bickering, their bond is deep-rooted, and their interactions often reveal an underlying affection.

The story takes a turn when a new transfer student, Aki Adagaki, enters their lives. Aki is cheerful, kind, and quickly becomes popular among their peers. Her arrival introduces a romantic tension, as both Shuro and Marin begin to develop feelings for her. This love triangle becomes the focal point of the narrative, with Marin determined to win Aki's affection while simultaneously trying to outdo Shuro in every possible way. The dynamic between the three characters is marked by humor, misunderstandings, and moments of genuine emotional depth.

As the story progresses, the rivalry between Shuro and Marin intensifies, but it also becomes clear that their constant competition is a way for them to express their feelings for each other. The series explores themes of friendship, rivalry, and the complexities of young love, blending comedic elements with heartfelt moments. The characters' growth is evident as they navigate their emotions and relationships, with each chapter adding layers to their personalities and interactions.

The manga balances lighthearted comedy with the emotional stakes of a love triangle, creating a narrative that is both entertaining and engaging. The interactions between Shuro, Marin, and Aki are central to the story, driving the plot forward while highlighting the nuances of their relationships. The series captures the essence of youthful romance and the challenges of understanding one's own feelings, making it a compelling read for fans of the genre.