Kyōka Jirō trains as a professional hero in U.A. High School's Class 1-A. Her Quirk, Earphone Jack, manifests as flexible plug-like jacks extending from her earlobes, functioning as prehensile appendages that stretch several meters. These jacks enable her to detect faint sounds and vibrations by plugging into surfaces for reconnaissance. Offensively, she channels her heartbeat into powerful soundwaves through her jacks or specialized equipment, generating destructive vibrations capable of shattering rock and disrupting enemies. Her signature moves are Heartbeat Distortion to crack the ground, Heartbeat Surround for close-range attacks, Legato for amplified sound assaults, and Counter-Balance to nullify sound-based attacks. Her equipment includes Stereo Boots for directional sound projection, forearm amplifiers called Amplifier Jack, and later, a prosthetic ear replacing her left earphone jack destroyed during the Final War. Petite and fair-skinned, Kyōka has dark purple hair styled in an asymmetrical chin-length cut featuring soundwave-shaped highlights. Her most distinctive features are her earphone jacks and triangular onyx eyes. Her hero costume evolves from an initial black leather jacket, salmon-colored shirt, ripped hemline, black pants, choker, and stereo-equipped boots to include headphones and forearm amplifiers. Post-Final War, her costume incorporates a sleeveless black jacket over a white tank top, silver-purple headphones, and black amplifier gloves. Eight years after the Final War, she grows taller, sports shoulder-length hair, ranks as the No. 30 Pro Hero, mentors Eri, and pursues music. Kyōka exhibits a pragmatic, blunt, and often unenthusiastic demeanor, frequently directing snark or physical jacks-as-whips toward classmates like Denki Kaminari or Minoru Mineta. Beneath this lies a deeply empathetic and protective nature, especially toward friends like Momo Yaoyorozu. She is organized and strategically adept, devising plans leveraging allies' Quirks, such as using Kaminari's Electrification at U.S.J. or Koji Koda's animal communication during exams. Her insecurities include self-consciousness about her appearance and initially viewing her musical passion as unrelated to heroism. She fears horror scenarios and avoids nudity. She overcomes her embarrassment to embrace music during the U.A. School Festival, performing lead vocals and inspiring classmates. Key relationships include her parents, Kyotoku and Mika Jirō, who support her hero ambitions; Momo Yaoyorozu, her best friend and tactical partner who creates equipment for her Quirk; and Denki Kaminari, a frequent teammate whose recklessness contrasts her caution. Their dynamic involves mutual support, like Kaminari encouraging her music during the Festival and Kyōka motivating him during life-threatening battles such as the Gunga Mountain raid. While their proximity as professional heroes eight years post-war sparks speculation, both explicitly deny romantic involvement, affirming a platonic bond. Kyōka participates in key battles: the U.S.J. incident, using sound detection to locate villains; the Provisional License Exam, using vibrations to disrupt groups; and the Paranormal Liberation War, where her resolve against All For One inadvertently stirs rebellion in his vestige world. During the Final War, she loses her left ear and jack but continues fighting. Her intellect is reflected in her academic ranking (7th in midterms) and resourcefulness, such as coordinating with Mashirao Ojiro and Mezo Shoji against Nine on Nabu Island. Post-graduation, she balances hero work with music, integrating her personal passions into her heroic identity.