Eijiro Kirishima/Relationships

Denki Kaminari
Since they happened to be seated behind one another in class, they became friends and often make comments to each other. They were later assigned to work together along with Katsuki for the Provisional License Exam. They have similar, congenial personalities, although Eijiro is more boisterous compared to Denki, who is more mischievous.

Katsuki Bakugo
Eijiro and Katsuki are on very good terms with each other. They're often times seen together during class, and despite Katsuki's aggressive behavior, it's been indicated that the two of them are friends. Eijiro has described Katsuki as being "manly," a quality that Eijiro is known to admire.

Before getting to know each other, it’s suggested that Eijiro did not admire Katsuki, as is seen in the Battle Trial arc. Eijiro criticizes Katsuki’s fighting tactics as “unmanly,” a discredit to Katsuki’s hit-and-run tactic. Later, however, while working together in the Unforeseen Simulation Joint arc, the two team up, soon sparking Ejiro’s admiration for Katsuki, and what would turn into a friendship as time goes on. Ejiro goes on to describe Katsuki as “manly” on a few occasions, a clear sign of respect for him.

During the Sports Festival, Katsuki called Eijiro "hedgehog hair", which irritated Eijiro who pointed out his similar hairstyle. Eijiro asked Katsuki to let him join him during the cavalry battle after Eijiro couldn't join Shoto Todoroki's team. Regardless, Katsuki accepted Eijiro's proposal after Eijiro mentioned taking down Izuku Midoriya's team. He later called Eijiro by his last name, showing he has come to respect or acknowledge him.

Due to his upbeat personality, Eijiro is usually unfazed by Katsuki’s abrasive behavior. When Katsuki’s divisive attitude arises, Eijiro often makes an effort to subdue it. Eijiro has also been known on occasion to criticize Katsuki's demeanor, as in the Provisional License Exam. During the School Trip arc, Eijiro was very worried for Katsuki when it’s announced that the villains were looking specifically for Katsuki. He also initiates the mission to rescue Katsuki after he’s kidnapped, while calling him his friend.

As noted by Izuku, Eijiro is the only one in their class who can call out to help Katsuki without hurting Katsuki's pride, which was proven true and shows that Katsuki may also view Eijiro as a friend.

During the Hero License Exam Arc, Denki stated that Katsuki had reduced the power of his explosions to avoid harming Eijiro and himself.

When Eijiro was sad about almost getting he and his classmates expelled, Katsuki paid him back for the 50,000 yen night vision goggles Eijiro bought to rescue Katsuki. When Eijiro openly voices his self-doubts, Katsuki reminded Eijiro that Eijiro proclaimed he's an unwavering horse during the Sports Festival and says Eijiro can be as strong as All Might if he refuses to go down. Eijiro later thinks of this the first time he uses Red Riot Unbreakable.

Tetsutetsu Tetsutetsu
Eijiro and Tetsutetsu initially had a rocky relationship because of their similar Quirks. During the U.A. Sports Festival, they met when they both survived being crushed by a 0-Point Villain. As the festival progressed, Eijiro resented being constantly compared to Tetsutetsu, like when Present Mic gave them similar intros prior to their match against one another.

After Eijiro defeated Tetsutetsu in an arm wrestling match, he congratulated the latter on a battle well fought, starting their eventual friendship. In Eijiro's next match, Tetsutetsu cheered for him to knock Katsuki out.

They both proved to be on good terms with each other when they ended up interning together at Fourth Kind's Hero Agency. They were initially surprised to see each other, but instead of lamenting about comparisons, they friendly greeted each other.

Hanta Sero
Eijiro and Sero are good friends with each other. Hanta, Denki, and Eijiro are often seen hanging out together.

Izuku Midoriya
Eijiro is on good terms with Izuku. In the Unforeseen Simulation Joint Arc, when Izuku was wounded from trying to help All Might with Tomura Shigaraki, Eijiro tried to help him.

In U.A. Sports Festival Arc, after Shoto told Izuku that he will defeat him, Eijiro tried to stop any further arguing and when Izuku started to talk negatively about himself, Eijiro tried to encourage him. He also told Izuku that he is envious of his Quirk.

He also seems to admire Izuku's growing confidence and seems to be impressed by his quick thinking and logical reasoning. He also seems capable of understanding Izuku's feelings to some extent, understanding how he felt when he was unable to rescue Katsuki.

Eijiro also asked Izuku to help him in his plans to rescue Katsuki from the League of Villains, since he knew they were close. In return, Izuku was aware of the bond Eijiro shares with Katsuki, which gave him an idea for Eijiro to be the one to retrieve him and it worked.

In the Internship Arc, Eijiro and Izuku are shown to be on even better terms than previously, often interacting in friendly ways.

Mina Ashido
Eijiro gets along well with Mina despite not interacting with her as much as he does with some of his other classmates. The two collaborated together on Team Bakugo during the Sports Festival Arc and seemed to work well together.

It was revealed that the two went to the same middle school, during their senior year, Eijiro tried to stop two students from bullying an underclassman but did not succeed. Afterwards, Eijiro witnessed Mina step in and solve the issue by getting the student and the two bullies to break dance, diffusing the situation and ending the issue. One of Eijiro's friends points out that Mina is very athletic, outgoing, strong and eye-catching while Eijiro and the others are boring. Eijiro seems to admire Mina for this but also begins to feel self-conscious of the fact that Mina is exciting and heroic. This is reinforced later when he attempts to stop a villain on the same day as the bullying incident but his legs freeze up and Mina stops the villain instead.

Kirishima later apologizes to Ashido and her classmates for not being able to do anything to stop the villain. Eventually, he and Mina both take the U.A. entrance exam together and pass. On their first day of high school, Kirishima undergoes a complete appearance change, dying his hair red and spiking it up in a style that is inspired by Crimson Riot. His hairstyle also appears to have two little horns, Mina picks up on this and decides to call themselves horn buddies. It's at this moment that Eijiro vows to say goodbye to his pathetic old-self to her and swears that he's gonna be the kind of hero that never has any regrets. The past incident took a toll on Kirishima's self-confidence, the guilt was eating him alive. Mina realizes this so she teases him and lightens the mood by poking him repeatedly and telling him not to overload himself with pressure. She shows concern for him in her own playful way. She asks him how he's going to move on and say goodbye to his old-self if he's still pulling the same-old gloomy face as before. Mina then smiles at Kirishima and tells him to tell her when he really does overcome his regrets from the past. Kirishima smiles back at her in agreement and apologizes.

She is shown to express concern for him, checking to see if he's moved on from his past yet.

Crimson Riot
Eijiro idolizes a retro pro hero called Crimson Riot and desires to become a hero just like him. Eijiro chose his Hero Name "Red Riot" to pay homage to him. In middle school, when Eijiro was questioning his dream of becoming a hero, it is old footage of Crimson Riot that reignites his passion for heroism. Eijiro shares many of his values with Crimson Riot, most notably Crimson Riot's high regard for manliness and chivalry.

Rikido Sato
They were paired up together in the final exams against Ken Ishiyama and they got along.

When the students moved into dorms, Eijiro was jealous at the popularity Rikido was getting for baking a cake and enjoyed the cake.

Tamaki Amajiki
Eijiro and Tamaki have a senpai-kouhai relationship since they both are in an internship under Fat Gum's care. Eijiro holds a lot of respect for his senpai as we see him praising the latter abilities multiple times and refusing to let go of the criminal who had previously shot Tamaki. He is also shown to be thankful for his senpai because it's thanks to him if he could join Fatgum team.

Later, in the operation to save Eri, Eijiro expresses confidence in Tamaki's abilities to take care of three enemies. In return, the latter respects Eijiro and compares him to Mirio saying they both have an "optimist personality."

Fourth Kind
Eijiro idolizes Fourth Kind and worked under him.

Fat Gum
Eijiro respects Fatgum and picked him for his internship, though he admits that he only picked Fatgum because Fourth Kind was unavailable. Eijiro is impressed by Fatgum's abilities as a hero and takes every advice he gives him really seriously. Eijiro's desire to protect Fatgum allowed him to go beyond his self-doubts and fears, meaning he cares greatly for the latter's safety.