Julia is a sixteen-year-old idol affiliated with 765 Production, who originally hails from Fukuoka Prefecture. Standing at 157 centimeters tall, she has short red hair, blue eyes, and a slender build. Her speech is often characterized by the particle "daze" at the end of sentences, and she uses the pronoun "atashi" when referring to herself, contributing to her cool and somewhat tomboyish demeanor.

Her background is unique among her peers, as she initially aspired to become a punk rock singer rather than an idol. She ended up at 765 Production by accident, having intended to sign with a rock-oriented agency. However, driven by a strong dislike for doing things half-heartedly and a genuine desire to move people with her songs, she decided to fully commit to her unexpected career as an idol. Her long-term goal remains to eventually succeed as a rock star, but she pursues her idol activities with complete dedication.

Despite her primary passion for punk rock, Julia is a versatile vocalist who has stated she can perform any genre, including pop, rap, and anime songs, if the occasion demands it. Music is central to her being, and she can become so absorbed in listening to or playing it that she becomes oblivious to her surroundings. She is highly proficient on the guitar, her listed special skill. An interesting detail is that, although she is left-handed, she plays a guitar designed for right-handed players to emulate a guitarist she respects.

Her personality balances her rock-and-roll attitude with a grounded, common-sense nature. She often acts as a straight man or a source of reason among her more eccentric colleagues, such as when interacting with the energetic Subaru Nagayoshi, whom she affectionately calls "Baka Subaru". While she usually shortens other idols' names, like calling Chihaya Kisaragi "Chiha" or Hibiki Ganaha "Bikki," she respectfully refers to Reika Kitakami as "Reika-nee". Despite her cool image, she can feel embarrassed by overly frilly or cute clothing, a sentiment she shares with Subaru. One of her notable flaws is her cooking, which is infamously terrible. She once produced food that she herself questioned was edible, though she showed significant improvement after being forced to practice during a "Survival Island" event.

Julia's role in the story often revolves around her relationship with music and her fellow idols. She was part of a band outside her idol work but left due to creative differences with its members. Her journey includes reconciling with her past and rediscovering her passion for collaborative music-making. She forms a key part of the unit Eternal Harmony alongside Chihaya Kisaragi, Emily Stewart, Matsuri Tokugawa, and Fuka Toyokawa. The story of this unit highlights her development as a performer, as she supports Chihaya, who struggles with the role of leader, showcasing Julia's empathetic and encouraging side. Her talent is further recognized in cross-branch collaborations, such as performing with the rock-influenced idol Natsuki Kimura from the Cinderella Girls series.

Notable abilities beyond her guitar playing and singing include a good knowledge of astronomy, which assists her in writing song lyrics about constellations. She holds a strong desire to perform live concerts and is a natural performer. Her artistic identity is such that "Julia" is explicitly stated to be a stage name; she is highly reluctant to reveal her real name, which is a source of personal embarrassment. The name "Pu-chan," used by the Futami twins, may be related to this secret. Over her career, she grows from a reluctant idol into one who finds the profession itself genuinely "rock and roll," fully embracing her place among the MILLION STARS.