Kota Izumi/Synopsis

History
Two years prior to the current story, Kota Izumi's parents, the Pro Hero duo Water Hose sacrificed themselves to save civilians from the villain Muscular. Believing they died a truly heroic death, many supporters praised Water Hose. Kota, however, was devastated by their deaths. Kota believed that his parents chose their work over him, and developed a twisted view of the world of heroes.

Kota was taken in by the Wild, Wild Pussycats, a hero team that Shino Sosaki (his last known relative) is a part of as Mandalay. Despite despising heroes, Kota listens to his relative and assists the Pussycats because he has nowhere else to go.

Forest Training Camp Arc
Students from U.A. High School arrive at the Pussycats' reserve to train for their summer break. The Pussycats introduce themselves but Kota remains silent. Pixie-Bob sends the students into The Beast's Forest and fights them using her Quirk to create dirt monsters. Kota watches the start of the fighting, but Mandalay tells him they're going back to base camp. Kota thinks their training is pointless, and that the students are stupid for wanting to become heroes. He snarls and leaves with Mandalay.

Class 1-A doesn't arrive at base camp for several more hours. Izuku Midoriya asks Pixie-Bob who's kid Kota is. Mandalay clears up the confusion and explains that Kota is her cousin's child. Mandalay asks Kota to introduce himself, but he remains silent.

Izuku walks over and greets Kota personally. Izuku outstretches his hand, but Kota instead greets him with a swift punch to the groin. Tenya Ida runs up to check on the blindsided Izuku and yells at Kota. Kota angrily replies that he refuses to hang around a bunch of wannabe heroes and storms off.

At dinner, Kota helps Mandalay with a box of vegetables. Later on, she places him on the wall splitting the boy's hot springs from the girl's, since Shota Aizawa warned them of Minoru Mineta's schemes. When Minoru tries to scale this wall in order to peep on the girls, Kota catches him at the top of the wall and tells him if he's going to be a hero, he needs to learn how to be a decent person. He pushes Minoru down the wall, garnering praise from the girls. Kota mistakenly looks back and sees the nude girls, causing him to faint and fall over the wall. Izuku catches him and brings him to Mandalay's office.

Mandalay thanks Izuku for saving him and explains Kota fainted from the fear of the fall. Izuku asks why Kota seems to hate heroes. Pixie-Bob enters the room and tells Izuku that Kota's parents were pro heroes who died in the line of duty. To Kota, his parents abandoned him for their hero work.

The next day, Kota silently watches Izuku train with Tiger from behind a tree. Later on, Kota opts not to eat dinner with everyone and ventures to his personal hideout. He's displeased when he realizes Izuku followed him there. Izuku brings him a plate of curry, but Kota says he doesn't need it and just wants Izuku to leave.

Izuku asks if Kota's parents were the Water Hose heroes, irritating the boy even more. Kota says people using Quirks to show off and calling themselves heroes and villains are what's wrong with the world. Izuku tells Kota a story about a "friend" who couldn't manifest a Quirk and how much he wanted to be a hero. Kota refutes Izuku and tells him to leave once again. Izuku leaves Kota alone with the plate of curry. During that night, Kota recalls Shino telling him that one day he'll meet someone that will help him understand heroes. Then he's distracted by the flames that have lit up the mountainside, shocking him with the chaos. A masked villain sneaks up on him from behind.

The villain says that he's surprised to find someone not on his hit list. Paralyzed in fear, Kota begins to cry and backs away from the man. The masked man prepares to kill Kota for his hat, just as the young boy recognizes him. He's the villain Muscular, the very same villain that murdered both of Kota's parents. Izuku suddenly arrives and rescues Kota just in time. Izuku promises to save him and engages Muscular. Kota watches in horror as Muscular overwhelms Izuku. Just before Muscular finishes Izuku, Kota throws a rock and asks Muscular a question.

Kota asks Muscular if he toyed with his parents Water Hose like he's doing to Izuku. He tells Muscular that he's what's wrong with the world. Muscular approaches Kota and tells him that he's wrong for wanting to shift the blame. The villain explains that he held no grudge for the loss of his eye, and that he only wanted to kill people and his parents wanted to protect them. He mocks their death by saying that the only tragedy is when a hero doesn't do what they set out to do, which is how their parents died.

Muscular then tries to kill Kota but Izuku rushes in and attacks Muscular from behind. He yells at Muscular for not taking the blame. Izuku explains that it's not a matter of whether or not heroes can do it. It is simply a hero's job to risk their lives to make their words into reality and then strikes Muscular with a maxed out punch.

Izuku's punch destroys part of the cliffside and nearly knocks Kota off on accident. Fortunately, Izuku catches Kota in time using his teeth and brings him back on land. Kota wants to thank Izuku, but he's horrified by the damage Izuku has taken for him. Muscular suddenly recovers from the attack, having used his muscles to absorb the damage. Muscular says he's going all out and attacks Kota and Izuku at full power. They narrowly evade a few of his attacks. Izuku tells Kota to flee while he holds the bloodthirsty villain back. Kota replies that Izuku is too injured to fight and they should both run away. Izuku reminds Kota that everything will be okay.

Muscular rushes them both at full strength and Izuku barely holds him back. Izuku tells Kota to run while he's being crushed by Muscular's muscles. Kota splashes Muscular using his Quirk and distracts him by yelling for him to let Izuku go. Muscular tells Kota that he’ll kill him in a minute and to be patient, but an outraged Izuku tells Muscular that he will never hurt Kota. Kota watches in amazement as Izuku defeats Muscular with one spectacular attack.

Kota cries as he remembers Mandalay talking to him about heroes. She said that he would meet someone that would risk their life for him. He questions why Izuku would do that for someone he doesn't know. Kota realizes heroes risk their lives to save people so that one day someone can call them "My Hero".

Izuku slowly recovers from the fight and tells Kota there are still more people he can save. Kota worries about Izuku's condition but Izuku is only focused on helping others. He even asks Kota to help his friends by using his Quirk to put out the forest fires. Izuku carries Kota through the forest until he runs into his teacher, Shota.

Izuku trusts Kota's safety to Shota. Shota rushes Kota to the facility and Kota cries on their way there. Kota wonders if Izuku will be alright, crying that he did not get a chance to apologize. Shota tells Kota that Izuku will be alright, advising him to thank Izuku the next time he sees him and to make his apology sincere.

At the facility, Shota asks Vlad King to look after Kota. The Vanguard Action Squad's attack ends after Katsuki Bakugo is captured.

Two days later, the doctor at the hospital Izuku is currently in hands him a letter from Kota. The letter thanks Izuku for saving him, while apologizing for hitting him as well, and hopes that Izuku gets well soon so that he can thank him in person.

Hideout Raid Arc
As the Pussycats comfort Tomoko Shiretoko over the loss of her Quirk and career, Kota watches solemnly from another room.

Pro Hero Arc
When the Pussycats paid a visit to U.A., Kota accompanied them to the dorms where he met Izuku again. The latter was happy to see him again and thanked him for the letter. Kota awkwardly tries to tell him it was nothing.

Shino soon pointed out Kota's new shoes, which are red high tops that look very similar to Izuku's own signature shoes. Kota became embarrassed after Izuku pointed out the match. According to Shino, Kota made a big fuss when his new shoes were bought, saying that they had to be red.

Dark Hero Arc
After the country fell into chaos following the events of the Paranormal Liberation War, Kota became one of the refugees who relocated to U.A. High School, being under Tomoko's care. When Class 1-A manages to bring Izuku back to the U.A., Kota witnesses the enormous hostility displayed by many of the refugees towards him, for fear that he will attract trouble.

When Izuku collapses into tears following Ochaco Uraraka's speech about why he should be allowed to rest, Kota breaks away from Tomoko and runs up to him, remembering the time when he bought the red shoes like Izuku's. He and a civilian Izuku saved approach him to comfort him. Unable to hold back his tears, Kota apologizes for not running up to help him sooner, but when he heard Ochaco speak, he knew he had to move. Kota admits how much he admires Izuku and wants to be like him and tells the older boy that he does not have to cry any more; Izuku is moved to hear this from him.

After the civilians agree to let Izuku in to rest, Kota runs up to hug him alongside Minoru as he is escorted inside by his classmates.

U.A. Traitor Arc
Sometime later, after Izuku has had enough time to rest and prepare, he and his classmates head out of U.A. to plan for the Final War against the Villains. As they say their thanks to the civilians, Kota approaches asking if he's leaving so soon, as Izuku tells him and everyone he's ready to head back out. Kota then says his goodbyes to Izuku alongside Eri.