Hinaki Shinjō attends Starlight School as a pop-style idol favoring the Vivid Kiss fashion brand. Her appearance features short, curly yellow-blonde hair styled in a feathered bob with a forehead braid secured by an orange star accessory, complemented by lime-green eyes.

Entering show business early through her parents' fashion industry connections, she modeled extensively alongside childhood friend Juri Kurebayashi. A rain-soaked live performance accident caused her hospitalization after a fall-induced unconsciousness, though injuries were minor. This event prompted overprotective staff behavior, leading Hinaki to suppress her individuality and prioritize others' expectations over her own preferences. Meeting Akari Ōzora sparked a transformation; inspired by Akari's authenticity, Hinaki embraced her unique identity and cultivated a personal fashion style.

She speaks informally using contractions like "Otsuka" for "Otsukaresama" and "Yoro" for "Yoroshiku," referring to herself as "Hina" while exhibiting energetic, approachable behavior. Her expertise spans beauty regimens, fashion trend analysis, and brand research, with favorite foods including acai fruit crepes, grapefruit, and vitamin C beverages.

Notable relationships include Akari Ōzora, whose freshness and authenticity inspired their friendship and formation of the unit Luminas with Sumire Hikami; Sumire Hikami, initially a formal classmate whose bond strengthened through Luminas; Juri Kurebayashi, a childhood friend whose evolving personality didn't disrupt their connection, later forming Passionate✮Jalapeño; and designer Kayoko, who rejected Hinaki's Premium Rare dress request three years pre-enrollment for lacking individuality but later approved her as a muse after Hinaki developed her distinct style.

Hinaki appears in *Aikatsu! 10th STORY ~STARWAY To The Future~* as part of the ensemble cast, within a narrative centering on Ichigo Hoshimiya's graduation decisions and the duo unit Cosmos involving Akari.