Kyoka Jiro hails from Shizuoka Prefecture, born to musicians Kyotoku and Mika Jiro. She inherited her mother's Quirk, Earphone Jack, manifesting as flexible, plug-like jacks extending from her earlobes capable of detecting vibrations and emitting amplified sound waves. Influenced by her parents' music careers, she learned multiple instruments like guitar and drums, yet chose to pursue heroism despite initial concerns about diverging from family expectations; her parents fully supported this decision. Enrolling at U.A. High School in Class 1-A (Student No. 12), Kyoka demonstrated academic competence, ranking 7th in midterm exams and 17th in the Quirk assessment test. Her pragmatic, blunt personality often surfaced in snarky interactions, particularly with Denki Kaminari and Minoru Mineta, though she maintained close friendships like the one with Momo Yaoyorozu. She exhibited insecurities about her less curvy physique and discomfort with overtly feminine attire, reacting strongly when omitted from Mineta's inappropriate comments. Key battles showcased her strategic Quirk use. At U.S.J., she collaborated with Momo and Denki, plugging her jacks into stereo-equipped boots to amplify vibrations that stunned villains, enabling Denki's wide-range electrocution. During final exams, partnered with Koji Koda against Present Mic, she devised a plan exploiting his insect phobia, using her jacks to expose underground bugs for their escape. Her combat repertoire expanded with techniques like Heartbeat Distortion (shattering ground via seismic vibrations) and Counter-Balance (nullifying sound-based attacks). A pivotal arc involved the U.A. Cultural Festival, where she reconciled her musical passion with heroism. Leading Class 1-A's band as bassist and vocalist, her performance of "Hero Too" united the audience, alleviating tensions and solidifying music as integral to her hero identity. In the Paranormal Liberation War and Final War arcs, she served critical reconnaissance and combat roles. Interning under Gang Orca, she honed her sensory abilities by training her jacks to penetrate stone cliffs for enhanced vibration detection. Facing All For One, she lost her left ear and jack to an explosion but defiantly channeled her heartbeat to disrupt his vestige realm, inciting rebellion among stolen Quirks. Post-war, Kyoka graduated from U.A. and became the No. 30 Pro Hero. She adopted a prosthetic ear with a functional jack, updated her costume with silver-purple headphones and forearm amplifiers, and grew her hair to shoulder length. She mentors Eri, balancing hero work with a music career. Her hero agency operates adjacent to a significant ally's, reflecting her enduring collaborative ethos.