Hiro Kurusu sports wavy, medium-length light-brown hair swept to the right, brown eyes, and multiple earrings adorning her right ear. She cultivates a fashionable look yet keeps her nails trimmed short for koto performance. Her standard outfits feature Tokise High School uniforms—a summer version with a light blue blouse and a winter set pairing a beige vest over a white blouse with a checkered brown skirt, blue socks, and brown shoes. A junior high betrayal shaped her worldview when a transfer student turned friends and her boyfriend against her through false accusations, convincing her human connections were fragile. She tested this by infiltrating seemingly tight-knit groups to spread discord and expose instability. Witnessing the Tokise Koto Club’s performance, she joined under false pretenses, feigning admiration while plotting to dismantle their bonds. She manipulated members by falsely claiming Satowa Hozuki dismissed the club as a "temporary haven" and scorned their skills to undermine trust. Exposed, she confronted club president Takezo Kurata anticipating condemnation. Instead, he offered understanding if she shared her motives sincerely, sparking initial confusion that later prompted reflection. Satowa Hozuki then confronted Kurusu, acknowledging their shared envy of the club’s authentic joy in koto. This admission, combined with the group’s acceptance of her apology, motivated Kurusu to rejoin authentically. She evolved into a devoted member, rising to vice president and exhibiting fierce loyalty. Her protective instincts surfaced when advocating for the club against external pressures and comforting younger members like Kota Mizuhara during his struggles. Romantic tension with Kurata deepened when he shielded her from accusatory former acquaintances during a shopping trip, physically defending her and silencing their slurs. This act intensified her emotional reliance on him, though their bond remains unspoken. Kurusu anchors the club emotionally, lifting spirits during doubt or stress. She encourages Satowa through social challenges and supports Chika Kudo through injuries, reflecting her role as an empathetic stabilizer. Her commitment extends to logistical efforts like securing her uncle’s inn for training camps, underscoring her dedication to collective goals.