Kyoka Jiro

Kyouka Jirou (耳郎響香) is a student at Yuuei training to become a Pro Hero.

Appearance
Kyouka has short purple hair and asymmetric bangs. Her most notable feature is her plug-like earlobes which seem to be able to change length. She has so far only been shown wearing the standard Yuuei school uniform and gym clothes. Unlike the other students, she wears a vest over her schooluniform.

Her hero costume consists of a black jacket, long peach-colored shirt, black pants, and boots with stereos in them. She also sports two small, red triangle facial marks just below her eyes, a plain black choker, and orange finger-less gloves.

Personality
She is pragmatic, unenthusiastic, and rude. Though she may be cold on the outside, she has a girly side on the inside.

Ultimate Space & Jams Arc
Kyouka is warped to the mountain area of the Ultimate Space and Jams along with Momo Yaoyorozu and Denki Kaminari. Annoyed that Denki is talking too much, she kicks him into one of the villains, causing the villain to be electrocuted by Denki's Quirk. She then uses her Quirk to protect Denki from an attack by one of the villains. Kyouka uses her Quirk to create a soundwave, causing the villains to block their ears in pain, which gives Momo the time needed to create an insulator sheet. Kyouka and Momo hide under the insulator sheet while Denki discharges a great amount of electricity, defeating the villains while Kyouka and Momo remain unharmed. However, one of the villains take Denki hostage, forcing Kyouka and Momo to stop and do nothing. However, the villain holding Denki is shot down, freeing Denki and Kyouka rushes to tie up the villain. She is then seen with her class after the battle with the Villain Alliance is over.

Sports Festival Arc
After Shouta announces that the Sports Festival is approaching, Denki says that he plans to become a professional Heroes's sidekick after he graduates, to which Kyouka states that many people become sidekicks and fail to become real Heroes, to which she thinks that Denki is the kind of person who would become like that, which causes Denki to become crestfallen. Kyouka competes in the Obstacle Race where she places 21st, allowing her to compete in the Human Cavalry Battle. In the Homan Cavalry Battle, she teams up with Rikidou, Kouji Kouda and Tooru Hagakure while Tooru is the rider. When the Human Cavalry Battle begins, Kyouka uses her Quirk to try and grab Izuku's headband when Tetsutetsu Tetsutetsu told her, but Fumikage uses his Dark Shadow to block her attack. Later in the Human Cavalry Battle, her team charges towards Shouto Todoroki's team, but her team gets zapped by Denki and frozen by Shouto's team. Her team fails to qualify to the next round when her team lost the Human Cavalry Battle.

After Denki and Minoru state that the girls must do the cheering battle as per orders from their homeroom teacher, Kyouka and the other girls of Class 1-A walk out in cheer leading outfits. However, as Kyouka and the girls walk out, they realize they have been tricked. Kyouka then calls Denki and Minoru idiots. During the recreational events, Kyouka is seen sitting still in her cheerleader outfit while watching Mina, Ochako, Tsuyu, and Tooru cheer lead. As the match between Ochako and Katsuki begins, Kyouka comments that she might look away the entire time. During the match between Ochako and Katsuki, Kyouka averts her eyes from the match when seeing Katsuki's explosion assault on Ochako.

Kyouka along with her class watches the closing ceremony of Yuuei's Sports Festival.

Field Training Arc
Two days after the Sports Festival, Kyouka is in class. During the Hero Informatics period, Class 1-A has to decide on Hero names. Kyouka gives Denki an idea for his Hero name, causing Denki to reply that her idea was intellectual, horrified that she was complimented for her intelligence. Kyouka writes down and shows her Hero name to her classmates. Kyouka reveals her Hero name to be Earphone Jack, the Hearing Hero.

After Class 1-A have finished formulating their Hero names, Kyouka is given a list of 40 work places in order to choose a work place that she would like to train at. On the day of the work place training, Kyouka is at the train station with her class so that she can go to the work place of her choice by train.

The workplace training comes to an end and Kyouka returns to Yuuei.

After Foundational Hero Studies is finished, Kyouka is in the girls' locker room. Kyouka uses her earphone jacks to hear Minoru's plan to peek on the girls. Kyouka plugs one of her earphone jacks into the hole which stabs Minoru's eye, stopping Minoru from peeking. Kyouka wonders why she was the only one he didn't mention.

End of Term Test Arc
One week before the end of term test, Kyouka asks Momo to help her study. Throughout the final week before the end of term test, Kyouka studies under Momo's tutoring along with Denki, Mina, Mashirao and Hanta. On the day of the exercise test, Mr Principal reveals that Class 1-A will be fighting against Yuuei's teachers for their exercise test. Kyouka is paired with Kouji and they must face Present Mic in their exercise test.

Kouji, Kyouka and Present Mic arrive in an uninhabited city where Class 1-A's test exercise will take place. In the city, Kyouka mocks Present Mic for what she takes as a poor reference, to which Present Mic tells her to be careful with what she says. Present Mic explains the 30-minute test; Kyouka and Kouji must either handcuff him or one of them must escape the battlefield within 30 minutes in order to win and pass the test. The test begins.

Kyouka plugs in her Earphone Jacks to try and block out Present Mic's loud voice, but to no avail. Annoyed by Present Mic's loud voice, Kyouka tells Kouji to command the nearby animals to attack but Kouji is unable to due to Present Mic's voice making the animals wild and as a result, any command he gave would be useless.

Kyouka and Kouji manage to get a little closer to the escape gate, but Kyouka notes that Present Mic will be at the escape gate and that no matter what option of victory they choose, a standoff is inevitable. Present Mic uses his loud voice again; Kyouka notes that they cannot get any closer as long as Present Mic is using his Quirk. Kyouka sees an ant and comes up with an idea; she asks Kouji if he can control bugs but his terrified reaction indicates that he doesn't like bugs. Present Mic uses his loud voice once again; Kyouka tries to counteract with her Earphone Jacks' but the sound of her heartbeat doesn't do anything against Present Mic. Present Mic continues using his loud voice against Kyouka and Kouji who are unable to handle it. Out of options, Kyouka asks Kouji if he can control insects to which he approves. Kyouka uses her Earphone Jacks to break a rock which reveals dozens of insects, much to Kouji's terror. Kyouka tells Kouji that she understands his phobia but using the insects to attack Present Mic is the only plan she can think of because their opponent is too strong. Kyouka encourages Kouji to follow through with her plan. After seeing Kyouka's bleeding ears, Kouji is ashamed that he is running away from this fight and realizes that he can only continue being at Yuuei by overcoming his fear. Kouji musters up the courage and commands the insects to attack Present Mic. At the escape gate, Present Mic sees that time is nearly up. Suddenly, dozens of insects crawl on Present Mic, who realizes that the insects traveled to him by moving underground; a place where sound is ineffective. Present Mic is paralyzed by fear, allowing Kouji to run through the escape gate while carrying an injured Kyouka with him; thus they pass the practical test.

Back at Yuuei in class, Kyouka learns that she has passed the written test and will go along with her classmates to the forest lodge which is a boot camp. Kyouka accompanies her class to the Kiyashi Ward Shopping Mall to buy necessities for the forest lodge. At the shopping mall, Kyouka says that she requires a big carrying bag, to which Momo tells Kyouka that she will help her look for it.

Quirk and Abilities
Earphone Jack: Kyouka's Quirk allows her to plug the jacks that hang from her earlobes into all sorts of things and channel the sound of her heartbeat into them; the vibrations cause havoc inside the objects. Kyouka can use her earphone jacks to catch sounds, giving the her the ability to hear across even extremely thick walls. Kyouka can use her earphone jacks like a whip in combat; it can stretch up to 6 meters and the sound radius is approximately 12 meter radius range. Kyouka's Earphone Jacks are strong enough to shatter rocks.
 * Cancelling (相殺): This move allows Kyouka to block out other sounds.

Ultimate Space & Jams Arc

 * Momo Yaoyorozu, Kyouka Jirou & Denki Kaminari vs. Villains: Win

End of Term Test Arc

 * Kyouka Jirou & Kouji Kouda vs. Present Mic: Win

Denki Kaminari
During the Battle Trial Arc and the Ultimate Space & Jams Arc, they were teamed together. Kyouka is somewhat really rude towards Denki. Whether it's because of her personality or because she just acts like that towards him, is not known yet. She tried to rescue him when he was taken hostage.

Momo Yaoyorozu
During the Ultimate Space & Jams Arc they were teamed together, along with Denki. They seem to have good teamwork and are buddies together.

Trivia

 * Kyouka the student No. 12 in Class 1-A
 * During the Quirk Apprehension Test made by Aizawa, Kyouka ranked 17th.
 * In the First Popularity Poll, Kyouka ranked 16th.
 * Kyouka can use her earlobes as earphones.
 * Kyouka's name has the kanji "耳" (mimi), which means "ear", and "響" (hibiki), which means "resonance, sound".
 * Kyouka likes rock.
 * Kyouka can play bass.
 * Technically, this is the very first quirk that's Horikoshi came up with.