Hinaki Shinjō is a pop-type idol at Starlight School affiliated with the brand Vivid Kiss. She has short, curly yellow-blonde hair styled in a feathered bob, featuring a braided strand across her forehead secured by an orange star clip, and distinctive lime-green eyes. Her height is 154 cm.

Energetic and informal, Hinaki connects easily with others, though her cheerful exterior masks insecurities cultivated during her long entertainment career since childhood. Her extensive experience once made her feel her contributions lacked freshness, leading her to suppress personal ideas to avoid worrying others—a habit formed after falling onstage during a rainy performance and subsequent hospitalization. Overprotective staff reinforced this until meeting Akari Ōzora, whose genuine approach inspired Hinaki to reclaim her individuality and "pop" again.

Hailing from a fashion-focused family with parents in the magazine industry, Hinaki debuted early with their support, securing numerous jobs including collaborations with childhood friend Juri Kurebayashi. Her career faced setbacks when designer Kayoko denied her a Premium Rare dress for lacking distinct style. After three years of self-discovery, Hinaki developed her unique fashion identity, ultimately earning Kayoko's approval and becoming her muse.

Her evolution centers on embracing originality. She shifted from imitation to cultivating her own style, vowing to make "every day a blast" through unique fashion. Key relationships fueled this growth: Akari reignited her passion; classmate Sumire Morohoshi shares mutual respect; and Juri reconciled with her after estrangement, forming the duo unit Passionate✮Jalapeño.

Hinaki uses informal speech with contractions like "Otsuka" and "Yoro," refers to herself as "Hina," and excels in beauty pursuits, fashion coordination, and brand research. Her traits include the Gemini zodiac sign, blood type B, and student ID 38031.