Kyoka Jirou is a high school student in Class 1-A at U.A. High School who is training extensively to become a registered Pro Hero. Physically, Kyoka is a short teenage girl standing at exactly 154 centimeters (about 5 feet 1 inch) tall. She possesses a remarkably slender, slight, and relatively flat-chested body build that lacks heavy musculature or voluptuous curves, maintaining a highly lean and agile frame optimized for rapid mobility and defensive repositioning. She has a fair, slightly pale complexion and sharp, distinct facial features. Her hair is a deep, dark purple-indigo color, cut short into an asymmetrical, messy bob that reaches just past her jawline, featuring a jagged fringe of straight-cut bangs that drape across her forehead. A highly notable physical characteristic is the unique pattern naturally forming on her strands, where light reflects off her dark hair to resemble the jagged lines of an electronic audio waveform. Kyoka has large, slanted, and down-turned eyes with dark, triangular-looking pupils and thin, expressive eyebrows. Her base facial expressions are typically characterized by a neutral, unbothered pout or a deadpan, slightly bored glare. A massive, defining biological anomaly of her anatomy is located on her ears. Hanging directly from the lobes of both ears is a pair of long, highly flexible prehensile cords that resemble real-world auxiliary headphone jacks, which can stretch, contract, and move completely under her voluntary motor control. Her supernatural physiological trait is a Mutant-type attribute known simply as Earphone Jack. This biological anomaly grants her the long, cord-like auxiliary jacks extending from her earlobes, which function as an organic extension of her auditory and nervous systems. Kyoka can plug these flexible plugs into any solid surface, structure, or object to channel the roaring acoustic vibrations of her own heartbeat directly into the environment. When plugged in, her heartbeat amplifies to a devastating volume, producing powerful, localized sonic shockwaves capable of shattering reinforced concrete, cracking solid stone barriers, and violently blowing back opponents from a distance. Her jacks also operate as an incredibly advanced, highly sensitive organic radar; by inserting the plugs into floors, walls, or the ground, she can catch microscopic sound frequencies, tracking the exact footsteps, movements, and vocal vibrations of targets across vast distances or behind thick obstacles. She can even catch the subtle electronic signals flowing through machinery. However, her trait features strict, punishing biological limitations tied directly to her physical hearing and nervous system. Because the power is tethered to her own ears, over-amplifying her acoustic output or experiencing sudden, massive counter-vibrations from enemy attacks inflicts excruciating sonic feedback on her eardrums. Pushing past her baseline tolerance causes severe auditory fatigue, headaches, ear bleeding, and temporary deafness, meaning she must carefully pace her output to avoid neural damage. Her personality is exceptionally cool, easygoing, and intensely pragmatic, serving as a laid-back yet fiercely reliable presence within Class 1-A. She is a remarkably sarcastic, dry-witted, and unpretentious teenager who frequently delivers blunt, deadpan commentary whenever her flashier or more ridiculous classmates behave dramatically. Kyoka possesses a deep, lifelong passion for rock music, playing multiple instruments expertly, though she initially hides this artistic talent behind a defensive wall of embarrassment, fearing that her musical hobbies are unsuited for a serious hero trajectory. She can appear slightly defensive, teasing, or unapproachable to strangers, particularly using her jacks to casually jab or restrain overly energetic peers when they cross her personal boundaries. However, beneath her edgy, aloof, and tomboyish exterior lies a deeply sensitive, empathetic, and insecure heart. She struggles with persistent anxieties regarding her own slender physical appearance, frequently comparing herself negatively to her more voluptuous female classmates. Despite these internal insecurities, she harbors an unyielding, incredibly brave spirit and a profound sense of duty. When dangerous crises emerge or villains ambush her group, her self-doubt vanishes completely, replaced by an admirable, steady focus. She never hesitates to put her own biological stamina and hearing on the line, utilizing her acoustic shockwaves and sonic radar to safeguard the people she cares about.