Earphone Jack grants its users long, controllable earlobes that work like headphone cables. Kyoka's earlobes are shaped like jacks at their ends, allowing her to plug them into a variety of objects. Those earlobes can further channel the vibrations of Kyoka's own heartbeats, dealing internal damage to said objects.
Moreover, Kyoka is able to catch faint sounds through her jacks even across extremely thick walls, making her excellent at scouting work. It is possible, however, to mislead her by somehow generating multiple sources of noise to mask the ones she's trying to detect.
Kyoka's earlobes can stretch up to 6 meters, and the radius of detectable sound is 12 meters. They are sturdy enough to easily pierce hard materials like concrete and able to act as additional limbs due to their prehensile nature, with Kyoka being capable of picking up small objects with them.
It's unknown if Mika has access to all aforementioned abilities displayed by her daughter.
Like any other part of her body, however, the Earphone Jacks are susceptible to damage and may suffer from overuse, evidenced when Kyoka's ears began to bleed from using her Quirk too much in a short time frame during the First Term Final Exam.
Kyoka's Quirk Factor lies within her ears and due to her losing her left ear during the battle against All For One, the use of her Quirk is now limited to just her right ear.
Kyoka uses her Quirk mostly for spying or support, making use of her jacks to detect vibrations caused by enemy movement. For offense, Earphone Jack can act as a sort of whip, with Kyoka using her jacks to shock targets with vibrations.
Kyoka can plug the jacks into the boots of her hero costume, which have speakers that allow her to shoot a concentrated blast of sound from her heartbeats in a specific direction. This technique, however, can be countered with a louder, opposing source of sound, such as Present Mic's Voice Quirk.
Earphone Jack is able to emulate actual headphones, evidenced by Kyoka plugging her jacks into electronic devices in order to listen to audio in private.
Named Super Moves
- Horikoshi mentions that Kyoka's Quirk is possibly the first Quirk he came up with, far before he'd even started planning My Hero Academia.
- My Hero Academia Manga and Anime: Chapter 16 and Episode 8.
- My Hero Academia Manga and Anime: Chapter 66 and Episode 36.
- My Hero Academia Manga and Anime: Chapter 104 and Episode 54.
- My Hero Academia Manga and Anime: Chapter 208 and Episode 97.
- My Hero Academia Manga: Chapter 355.
- My Hero Academia Manga: Chapter 320.
- My Hero Academia Manga: Vol. 3.