Hiroka Betsuyaku, nicknamed Hiro, is Suzu's closest friend and sole confidante, uniquely aware of Suzu's secret identity as the virtual pop star Belle. Her sharp wit, honed by extensive online engagement, equips her to counter internet negativity and harassment directed at Belle's rising fame. Hiro leverages technical proficiency and strategic management to maintain Belle's anonymity while coordinating her musical performances within the virtual world.

She possesses black shoulder-length hair, fair skin, and light brown eyes, often seen wearing red glasses. Her typical attire is a school uniform: a white shirt with a red ribbon bow and a dark blue skirt. Her parents enforce household rules, including banning her from using a specific room after her father questioned her activities there.

Beyond the virtual realm, Hiro actively supports Suzu through emotional challenges, including Suzu's unspoken romantic feelings for their physics teacher, Mr. Terada – evidenced by Hiro's discreet use of his photo as her phone's lock screen wallpaper, a secret Suzu discovers. Hiro also mediates relationships among peers, facilitating romantic confessions between classmates.

During the investigation into the Dragon's identity, Hiro collaborates with Suzu to uncover the truth about Kei's abusive home situation. She later joins the effort to locate Kei and his brother in Tokyo, aiding the resolution of their real-world crisis. Within the online world "U," Hiro operates under the virtual persona "eroh," designed by concept artist Ippatu.