Nina Iseri is the protagonist of the anime series Girls Band Cry, serving as the lead vocalist and later rhythm guitarist for the band Togenashi Togeari. She originates from a small country town in Kumamoto Prefecture, where she grew up in a strict family environment. Throughout her school years, Nina was an introverted and inconspicuous student with average grades, living her life by reading the atmosphere and adapting to those around her. However, after witnessing bullying at her high school, she intervened to defend the victim, an act that led to her own ostracization by her peers. The resulting isolation and mistreatment caused her to become a high school dropout, and she subsequently moved to Kawasaki, Tokyo, determined to prove that she can live independently and succeed on her own terms.

Beneath her quiet surface, Nina harbors intense emotions—anger, loneliness, and a deep-seated frustration with injustice. She is temperamental, prone to mood swings, and extremely stubborn, often struggling to regulate her feelings. Her defining trait is an unwavering sense of justice that makes her unable to tolerate hypocrisy or compromise. This leads her to confront others directly, even in public, to demand honesty and accountability. Fellow band member Subaru Awa nicknames her a "righteous monster" because of this uncompromising attitude. Nina’s core motivation is to live authentically and express her true self, which she ultimately channels through music. She seeks acceptance and belonging, but refuses to achieve them by pretending that unfairness is acceptable.

In the story, Nina is the driving force behind the formation of Togenashi Togeari. By chance, she meets Momoka Kawaragi, a former member of the idol rock band Diamond Dust, and they bond over their shared love of music and mutual experiences of being misunderstood. Together with other girls from different backgrounds—Subaru Awa, Tomo Ebizuka, and Rupa—they form a band as an outlet for their raw emotions and as a way to defy societal expectations. Nina’s role is central; her passionate vocals and emotional intensity give the band its distinctive sound and direction.

Key relationships include her close partnership with Momoka, whom she deeply admires and eventually confesses her romantic feelings to. Her friendship with Subaru is characterized by playful friction, as Subaru often teases her but also provides grounding support. Tomo and Rupa bring musical discipline and stability, balancing Nina’s volatility. Over the course of the series, Nina undergoes significant development. Initially burdened by self-doubt and a habit of putting others’ needs above her own, she gradually learns to confront her fears, embrace her individuality, and take the lead both on stage and in her personal life. A pivotal moment occurs in episode ten, when she reconciles with her family, particularly her father, who finally acknowledges her struggles and supports her musical ambitions.

Nina’s notable abilities lie in her vocal prowess and her capacity to convey profound emotion through song. While she has no supernatural powers, her performances resonate deeply with audiences, often evoking strong feelings and connecting with listeners on a personal level. Her emotional authenticity becomes the band’s greatest strength, allowing her to turn her anger and sorrow into powerful music that challenges the status quo.