Hinaki Shinjō attends Starlight School and pursues idol activities across multiple units. She performs as part of Luminas alongside Akari Ōzora and Sumire Hikami, and also in Passionate✮Jalapeño with her childhood friend Juri Kurebayashi. Representing the Vivid Kiss brand, she specializes as a pop-type idol.

Her appearance features short, curly yellow-blonde hair styled in a feathered bob. A braid crosses the right side of her forehead, secured with an orange star clip, complementing her distinctive lime-green eyes. She stands 156 cm tall, celebrates her birthday on June 11, is a Gemini, and has blood type B.

Energetic and informal, Hinaki easily connects with others. Raised in the entertainment industry from childhood, she possesses extensive knowledge of fashion and idol activities, though she sometimes feels her advice lacks freshness compared to newer idols. She champions individuality in fashion, believing suitable clothing exists for everyone.

Her parents worked at a fashion magazine and supported her early show business debut, which included occasional collaborations with Juri Kurebayashi. A pivotal incident occurred during a rainy live performance where she slipped, fell, lost consciousness, and was hospitalized. While not severely injured, the event caused staff to become overly protective. To ease their worries, Hinaki began suppressing her own ideas, prioritizing others' expectations over self-expression. This continued until meeting Akari Ōzora, whose authenticity inspired Hinaki to reclaim her individuality.

Her character development centers on embracing her unique style. Three years prior to the main events, designer Kayoko denied her a Premium Rare dress, citing a lack of distinct identity. Hinaki later demonstrated her developed fashion sense, earning Kayoko's approval and eventually becoming the designer's muse. This journey cemented her commitment to originality, leading to her declaration: "From now on, no more imitating. I'm going to make every day a blast with Hinaki Shinjō's own fashion!"

Key relationships define her idol path. She admires Akari Ōzora for her freshness, resulting in mutual positive influence, fast friendship, and the formation of Luminas. With Sumire Hikami, they evolved from formal classmates to close friends and unitmates. Her bond with Juri Kurebayashi endured despite Juri's personality changes, leading to reconciliation and the creation of Passionate✮Jalapeño. Her dynamic with Kayoko transformed from rejection to mutual inspiration.

Her favorite foods include açaí fruit crepes, grapefruits, and vitamin C beverages. Specialties encompass beauty regimens, information gathering, and brand research. Distinctions include being the only character initially denied a Premium Dress, achieving her second Premium Dress in six episodes (the second-fastest record), and sharing a singing voice with another character from a related series. Informal speech patterns, like using "Otsuka" instead of "Otsukare," and her self-referential nickname "Hina," further characterize her.

Activities include nationwide tours with Luminas during the fourth season, interacting with aspiring idols and participating in regional events. She engages in auditions, collaborations, and special performances, such as a space-themed drama and comedy routines with other idols. These experiences highlight her supportive role encouraging newcomers while continuing her own growth.

Hinaki Shinjō's journey encapsulates overcoming self-doubt, fostering genuine connections, and cementing her identity as an idol championing personal style and joyful self-expression.