Hiroka Betsuyaku, nicknamed Hiro, is Suzu Naito's best friend and primary confidante. Her sharp, witty personality stems from extensive online engagement. As the sole keeper of Suzu's secret identity as the virtual singer Belle in the online world "U," Hiroka actively safeguards this dual life to protect Suzu's privacy.

She has black shoulder-length hair, fair skin, and light brown eyes, frequently seen wearing red glasses and a school uniform comprising a white shirt with a red ribbon bow and a dark blue skirt.

Within "U," Hiroka operates under the alias "eroh," an avatar designed by concept artist Ippatu. Though she claims no secrets, her phone lock screen displays a picture of their physics teacher Mr. Terada—a hidden admiration causing embarrassment that she conceals from her parents, hinting at a potential crush.

Her parents, Mr. and Mrs. Betsuyaku, influence her life; her father questions her activities and bans her from a specific room in their house, a restriction communicated by her mother.

Hiroka leverages exceptional technological skills to investigate the Dragon’s real-world identity when Suzu resolves to help him. She tracks the Dragon’s "U" combatants, analyzes pixelated footage, and identifies background details to locate him. Initially skeptical of Suzu’s involvement due to safety and anonymity risks, Hiroka ultimately prioritizes Suzu’s resolve and provides crucial support despite reservations.

Driven by loyalty, she assists Suzu in protecting Kei and Tomo after uncovering their abusive situation, playing an instrumental role in shielding the brothers from harm.