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.

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.

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 and Tooru 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 he would like to train at. On the day of the work place training, Kyouka is at the train station with his class so that he can go to the work place of his choice by train.

Quirk
"Earring Jacks" - She can raise the sound of her own heartbeat but also catch very faint sounds with her plugs. She can also use it as a whip.

Battles
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Ultimate Space & Jams Arc
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 * Momo Yaoyorozu, Kyouka Jirou & Denki Kaminari vs. Villains: 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

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