Kota Izumi/Relationships

Water Hose
Despite the little interaction that is seen between them, it is evident that Kota felt a great affection towards his parents. However, their murders at the hands of Muscular caused Kota a profound shock. Kota believed that his parents chose their work over him, and developed a cynical and jaded view of the world of heroes.

Despite this, when he encounter Muscular, he reproaches their murders, showing that he still continues to love his parents. After Izuku comes to his rescue, he finally understands why his parents sacrificed themselves to protect the lives of others.

Shino Sosaki
After the death of his parents, Kota was left in the care of Shino Sosaki, his last known relative, and member of the hero team, the Wild, Wild Pussycats. Despite despising heroes, Kota listens to his relative and the Pussycats because he has nowhere else to go.

Because of his parents' deaths, Kota dislikes heroes in general. Shino understands the feelings of her second cousin, but tries to comfort Kota and explain that someday he will understand why his parents died.

After Kota being saved by Izuku, the relationship of the two improves. Shino realizes that Kota has started to admire Izuku as his hero.

Izuku Midoriya
Because of his contempt for heroes, Kota despised Izuku at first, he even went as far as hitting Izuku in the groin for trying to be friendly towards him. Despite this, after he comes to know of Kota's past, Izuku tried to get along with him, due to their similar circumstances of both being "Quirkless" (Izuku not originally being born with a Quirk and Kota refusing to use his Quirk). Izuku tells Kota a story about "a friend of his" who couldn't manifest a Quirk and how much he wanted to be a hero. Despite Izuku’s best efforts, Kota still refuted Izuku's attempts at friendship and tells him to leave once again.

Later, Kota is attacked by Muscular, the villain who murdered his parents, but is saved by Izuku. During the battle, Kota uses his Quirk out of desperation in an attempt to help Izuku. This distracts Muscular long enough for him to be defeated by Izuku with one spectacular attack. Since being rescued by Izuku, Kota finally starts to understand why heroes exist. Kota recognizes that Izuku had risked his life and taken significant injuries in a fight for someone he didn't know at all. Izuku shows him what it's like to be a real hero. From this, it is shown Kota has gained respect for Izuku.

While Izuku is in the hospital recovering from his injuries, Kota writes him a letter. The letter has him apologize for his assault on him and thanks Izuku for saving him and hopes that Izuku gets well soon so that he can thank him in person.

When they meet again a few months later, Shino points out Kota's new shoes to Izuku, which are red high top sneakers that strongly resemble Izuku's own signature shoes, much to Kota's embarrassment. According to Shino, Kota made a big fuss when his new shoes were bought, saying that they had to be red. Although he's too proud to admit it, this shows that Kota now looks up to Izuku.

When Izuku returned to U.A. and broke down crying, Koran comforted him, hugging him and telling him, “I am here!” Alongside Minoru, he would run up to hug him again once he reunited with his mom.

Other Class 1-A students
Kota initially despised Izuku's peers for working to become Pro Heroes, having looked down on them with his cynical opinion about heroes, much to the chagrin of Katsuki Bakugo. Tenya Ida reprimanded Kota for kicking Izuku in the crotch, demanding an explanation why he did so. Like most others, Kota is left unsettled and disgusted by Minoru Mineta's perverse behavior, having punched him off the wall for attempting to peep on the girls bathing. Mina Ashido thanks him on behalf of the other girls for punishing Minoru. Despite his young age, Kota himself gets flustered when he looks down at Mina and the other girls bathing.

Muscular
Kota saw Muscular in the report that detailed his parents deaths.

Kota came upon the villain while he was in his secret place, as the latter attacked him for his hat. Kota was saved by Izuku and watches him fight the villain. When Muscular unmasked himself, Kota realized he was the villain who killed his parents. Kota confronted him on this and was horrified after Muscular admitted with no remorse that he killed his parents. When he intended to do the same to Kota, Izuku once more intervenes. Kota watched as Izuku continued to fight Muscular and soon saved Izuku from a fatal blow, distracting the villain long enough for Izuku to regain strength and defeat the villain.