Asuka Ninomiya is a 14-year-old female with light orange hair accented by ever-changing colorful extensions. She stands 154 cm tall, weighs 42 kg, and has a February 3 birthday with blood type B. Her measurements are 75-55-78. Her signature outfit combines a purple t-shirt, black jacket, purple checkered scarf, black pants, and shoes. Personality-wise, she embodies chuunibyou (eighth-grader syndrome) through a subcultural, hipster lens. She consciously avoids mainstream interests, cultivating uniqueness via unconventional tastes. Her speech drips with obscure, dramatic phrasing—commenting on her heart's metaphorical cold rather than the weather. Openly acknowledging her prickly demeanor, she attributes it to adolescence and requests patience during tense interactions. Unlike fantasy-oriented chuunibyou, her nonconformity skews intellectual. Her hobbies include intricate hair arrangement and dyeing, radio listening, and manga drawing. She dislikes black coffee. Originally a rival idol in Shizuoka, she later joins the main roster as a producible idol. Her character evolves from isolation to forging bonds, particularly with kindred spirit Ranko Kanzaki. In Cinderella Girls Theater episode 13, she compliments Ranko's artwork, flustering her; during the 2015 anime's episode 25 performance, she winks at Ranko. She performs in unit CAERULA alongside Syuko Shiomi, Fumika Sagisawa, Kanade Hayami, and Arisu Tachibana. Solo songs include "Kyoumei Sekai no Ontology" and a "Skyclad no Kansokusha" cover. Group tracks feature "Saite Jewel," notable in Starlight Stage events. Her self-introduction reveals her defensive stance: "I'm Asuka. Asuka Ninomiya. I don't know you, but maybe you know me? Aah, you're probably thinking something like that right now... 'What a prickly person'. Well I'm an adolescent 14-year-old, so that's kind of normal..."