"Too Many Losing Heroines!" centers on a high school setting where romantic entanglements and unrequited feelings drive the narrative. The protagonist, a seemingly ordinary male student, becomes entangled in the lives of several female classmates, each of whom has experienced rejection or failure in their romantic pursuits. These "losing heroines" are characterized by their distinct personalities and emotional struggles, which stem from their past experiences with unreciprocated love.

The story unfolds as the protagonist inadvertently becomes a confidant and emotional support for these girls. Each heroine has a unique backstory, ranging from being rejected by a childhood friend to failing to confess their feelings to a crush. The protagonist’s role evolves as he navigates these complex relationships, often finding himself in situations where he must mediate or provide advice, despite his own lack of romantic expertise.

Key characters include a stoic class representative who hides her vulnerability, a cheerful and outgoing girl masking her pain with humor, and a shy, introverted student struggling to express her feelings. The interactions between the protagonist and these heroines are marked by a blend of humor, awkwardness, and genuine emotional moments, as they collectively grapple with themes of self-worth, acceptance, and the complexities of young love.

The plot progresses through episodic arcs, each focusing on a different heroine and her journey toward overcoming her emotional hurdles. While the protagonist does not actively pursue romantic relationships, his presence serves as a catalyst for the heroines to confront their insecurities and grow. The series balances lighthearted comedic elements with poignant reflections on rejection and resilience, creating a narrative that resonates with themes of personal growth and emotional healing.