Hiro Hayami reigns as an absolute idol, commanding overwhelming popularity among female fans with yellow roses symbolizing their unwavering support. Born into Tokyo poverty, his mother's inability to care for him led to placements in multiple foster homes, including a church, before their reunion in a dilapidated apartment. Discovering Prism King Cup tournaments through his mother’s phone ignited his passion for Prism shows and idol Hijiri Himuro. After Kou Norizuki witnessed Hiro dancing in a park, he offered an Edel Rose Academy scholarship, accepted by Hiro’s mother. Relocating to the Norizuki household, Hiro endured Jin Norizuki’s strict discipline, fostering deep indebtedness that silenced his dissent.

At Kakyoin Academy, Hiro’s top academic standing and Norizuki ties branded him a "teacher’s pet," isolating him socially until age 13, when he defended Mihama Kouji from bullies. Their friendship blossomed through shared admiration—Hiro inspired by Kouji’s musical genius and vision to revolutionize Edel Rose. Hiro confessed his true dream: not Prism Kingship, but becoming a hope-bringing "hero." Jin later manipulated Hiro into betraying Kouji, demanding Hiro claim authorship of Kouji’s song "Pride" as the price for a joint debut unit. Hiro’s compliance drove Kouji to angrily abandon Edel Rose. Hiro then manipulated Ito Suzuno to reclaim "Pride" for his solo debut, fracturing bonds further.

Desperate to break Jin’s control, Hiro challenged Kazuki Nishina in a Prism Show with Kouji’s songs as the prize. Kazuki performed "Freedom," Kouji’s coded message of reconciliation; recognizing lyrics echoing their past, Hiro forfeited. When Jin disqualified Bell and Naru from the Prism Queen Cup, Hiro publicly exposed Jin’s lies, apologizing to fans and Kouji. Though planning retirement, Hiro joined Kazuki and a returning Kouji in unit Over The Rainbow, mending trust through performances.

Later, Hiro supported Kouji’s move to America but rejected his offered song "Over The Sunshine," insisting on competing with "Pride." Louis Kisaragi of Schwarz Rose seized legal rights to "Pride," leaving Hiro songless for the Prism King Cup. A visit to Kouji in America escalated into a brutal Prism duel where Kouji condemned Hiro’s dependency. Defeated, Hiro returned to Japan demoralized until Edel Rose peers Yu Suzuno and Ito composed a new song, reviving his spirit. At the Prism King Cup, Hiro performed "Pride" despite disqualification risks—only for Kakeru Juuouin to reveal secured song rights. Hiro’s triumph crowned him Prism King before Kouji and Kazuki.

Beyond group endeavors, Hiro modeled and acted, co-starring with Naru Ayase in "Yoru no Yoshaman." Offstage, his calm, self-deprecating demeanor contrasts sharply with his charismatic stage presence. He wears glasses or contacts for visual impairment and habitually bites his thumb or glasses. Hiro’s idol ethos centers entirely on fan happiness, epitomized by his catchphrase: "Absolute Idol, Love N.G."