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, at first Kota despised Izuku. 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 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.

Later, Kota is attacked by Muscular, the murderer of 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 understands why heroes exist. Kota recognizes that Izuku has risked his life and taken a significant injury 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 shows Izuku the new shoes Kota brought, which are red ones just like Izuku's, much to Kota's embarrassment. Although he's too proud to admit it, this shows that Kota starts looking up to Izuku.

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.