"A Devil and Her Love Song" centers on Maria Kawai, a sharp-tongued and brutally honest high school student with a troubled past. Expelled from her prestigious Catholic school for an incident involving a teacher, Maria transfers to a new school, where her blunt demeanor and lack of social filters alienate her from her classmates. Despite her abrasive exterior, Maria possesses a deep emotional vulnerability and a passion for music, particularly singing, which becomes a key element in her journey.

The narrative explores Maria’s struggle to navigate her new environment while grappling with her reputation as a "devil" due to her perceived coldness and harsh honesty. Her interactions with classmates, particularly Yusuke Kanda and Shin Meguro, drive much of the story. Yusuke, a cheerful and popular boy, initially clashes with Maria but gradually becomes one of her few allies, drawn to her authenticity. Shin, a quiet and introverted classmate, shares a deeper connection with Maria, as both harbor emotional scars and a sense of isolation.

As the story progresses, Maria’s relationships with Yusuke and Shin evolve, revealing layers of their personalities and pasts. The series delves into themes of self-acceptance, the complexities of human relationships, and the power of communication. Maria’s journey is marked by her efforts to reconcile her honesty with the need for empathy, as well as her desire to connect with others through music. The manga balances moments of humor, drama, and introspection, creating a nuanced portrayal of adolescence and personal growth. The characters’ development is central to the narrative, with Maria’s transformation from an outcast to someone who learns to trust and open up forming the emotional core of the series.