"Heroine ni Naritai" centers on Hiyori Suzumi, a high school girl who aspires to become a heroine in her own life, inspired by the romantic and dramatic stories she reads in shoujo manga. Hiyori is determined to experience the kind of love and adventure she admires in fiction, but her reality is far from ideal. She is often overshadowed by her more popular and confident classmates, particularly her childhood friend and crush, Shiki Asagi, who is oblivious to her feelings.

The narrative explores Hiyori's journey as she navigates the complexities of adolescence, friendship, and self-discovery. Her attempts to emulate the heroines she idolizes often lead to humorous and awkward situations, highlighting the gap between her idealized fantasies and the messy, unpredictable nature of real life. As the story progresses, Hiyori begins to realize that being a "heroine" is not about fitting into a predetermined mold but about embracing her individuality and finding her own path.

Shiki Asagi, the object of Hiyori's affection, is a charismatic and carefree boy who is well-liked by everyone but remains emotionally distant. His interactions with Hiyori are marked by a mix of teasing and genuine care, though he remains unaware of her deeper feelings. Another key character is Satsuki Hinata, a quiet and observant classmate who becomes an unexpected confidant for Hiyori. Satsuki's calm demeanor and insightful advice provide a contrast to Hiyori's impulsive nature, offering her a different perspective on love and life.

The manga delves into themes of self-acceptance, the pursuit of dreams, and the challenges of unrequited love. Hiyori's growth is central to the story, as she learns to balance her romantic ideals with the realities of her relationships and personal aspirations. The series combines lighthearted moments with poignant reflections, creating a relatable and engaging narrative about the trials and triumphs of growing up.