Eijiro Kirishima

Eijiro Kirishima (切島鋭児郎) is a student at U.A. High training to become a Pro Hero.

Appearance
Eijiro has spiky red hair that resembles horns (which is not its natural appearance) and a little scar above his right eye that can be mistaken as a single long eyelash. Despite his young age, Eijiro possesses an impressive physique and a muscular body.

In his costume, he wears a vest that consists of two shoulder pads that are shaped like gears that wrapped around his shoulders while his chest is left uncovered, and wears a skirt with a ripped pattern over pants with an "R" belt. He also wears a mask that somewhat resembles the same mask that the main character of Akumetsu wears. His costume looks like an Aka Oni (red troll-like creature). During the Hero License Arc, his costume gains long crimson sleeves.

Personality
Eijiro is a very boisterous, outgoing guy with a fondness for the concept of manliness, often using the terms "manly" and "unmanly" to describe stuff he does or doesn't like. Those who showcase a noble, brave or determined attitude tend to emotionally move him to tears, quickly earning his complete admiration, respect and friendship. Similarly, he will call out traits that are the opposite of that, such as cowardice and dirty play. He is also a big fan of Crimson Riot, a retro hero that he takes inspiration from, including his own hero name.

Eijiro is honest and kind-hearted, with All Might praising his heroic spirit. In addition, he seems capable of making friends with most people, as he is one of the few classmates who is friends with both Katsuki Bakugo and Izuku Midoriya. Eijiro is very dedicated to his friends and is even willing to break the law and the rules in order to help them, showing regret if he becomes unable to do so.

Eijiro has stated more than once that he doesn't think very highly of his own Hardening Quirk, thinking that it lacks the flashiness usually found in the Pro Hero scene. In fact, he will get downright offended if he finds someone with a similar Quirk. Regardless, Eijiro is a confident and hot-blooded fighter, although not to the same degree as Katsuki. However, he does not shy away from comparing himself to Katsuki, with Izuku stating that the two have managed to develop a relationship between equals. Because of this, Eijiro is notably one of the few people that Katsuki holds some respect for.

History
When he was three years old, he was in bed and woke up since he had to go to the bathroom. When he rubbed his eye, his Quirk manifested for the first time. This made his hand harden and caused Eijiro to cut himself, which left a scar on his right eye.

Quirk Apprehension Test Arc
Eijiro Kirishima is first introduced when Izuku Midoriya arrives on the first day of class. He is sitting at his desk, alongside the other Class 1-A students. Shortly afterwards, the class makes their way to the P.E grounds, where Shota Aizawa informs them they must undertake a Quirk apprehension test. Eijiro is shocked by his teacher's announcement that student who places in last will be expelled.

Battle Trial Arc
The next day at school, All Might teaches Class 1-A's Basic Hero Training Class and announces that the class will participate in Battle Trials. Eijiro is excited by the idea of combat training and changes into his hero costume with the rest of his class. Eijiro is partnered with Hanta Sero on "Team J" after being randomly paired. While observing the battle between Katsuki Bakugo and Izuku Midoriya, Eijiro says Katsuki's unmanly for trying to ambush Izuku. He also questions what they're saying during the battle, as there's no sound through the surveillance footage. After witnessing Katsuki's large attack on Midoriya, Eijiro becomes increasingly concerned with Izuku's safety.

Watching the match between Shoto Todoroki vs Mashirao Ojiro and Toru Hagakure, Eijiro and All Might begin to shiver when Shoto uses his Quirk. Later on after the battle trials, when Izuku returns to class, Eijiro along with his other classmates surround him praising his performance during the Battle Trial and introduce themselves.

Unforeseen Simulation Joint Arc
During their next homeroom class, Mister Aizawa announces Class 1-A must choose a class president. Eijiro and his classmates are excited by the idea of representing their class. After voting, Izuku Midoriya is elected and Eijiro openly supports him.

Later on, the school sirens go off at lunch and students evacuate in a panic, creating a large traffic jam. Eijiro is caught in the mob, but the situation is diffused by Tenya Iida, who reveals it is a false alarm caused by the media trespassing on school grounds. Afterwards, Midoriya resigns as class president and elects Iida in his place. Eijiro supports the decision because he saw that Iida manned up and took charge of the previous situation.

Mister Aizawa interrupts and instructs the class to suit up and prepare to head out for rescue training. While on the bus traveling to an outside facility, Eijiro speaks with his classmates regarding Quirk's and their relation to pro-heroes popularity. He says that he wishes for a flashier Quirk, believing it would garner him more fame. Izuku argues that Eijiro's Quirk is strong enough to become a popular pro, but Eijiro restates his point by using Shoto and Katsuki as examples of Quirk's perfect for professional heroes.

The class eventually arrives at the Unforeseen Simulation Joint, greeted by Thirteen. But they are interrupted by the arrival of the League of Villains.

As the villains keep showing one after another, Eijiro is seen evacuating with his class, but they end up coming across Kurogiri, who blocks their way. Eijiro, together with Katsuki, attempt to attack the villain but are unsuccessful due to Kurogiri's amorphous body. The villain then uses his Quirk and warps Eijiro, along with Katsuki, to the Ruins Zone of the U.S.J.

In the Ruins Zone, Eijiro and Katsuki are ambushed by a group of villains, but both are able to hold their own and defeat them. Eijiro says that they should go and save the others, worrying about his classmates that don't have battle-effective Quirks. Katsuki, however, decides to go and fight Kurogiri instead, much to Eijiro's surprise. After hearing Katsuki's reasoning to go after Kurogiri, Eijiro notices Katsuki's calm attitude, much to Katsuki's chagrin. Eijiro decides to go with Katsuki.

Eijiro and Katsuki eventually reach the central plaza, where they get to attack Tomura and Kurogiri respectively. Eijiro attempts to punch Tomura, but the latter dodges it. Eijiro then shows his desire to support All Might against the villains, but the hero refuses, telling them to escape. Tomura attempts to attack Eijiro and the others, but All Might's fight with Noumu prevents him from getting near. Eijiro then witnesses Izuku rushing towards All Might, trying to help him.

After the other university teachers arrive and the villains retreat, Eijiro dashes towards Izuku and All Might in order to check their condition, with the latter fearing that Eijiro would see his true form. Fortunately, Cementoss blocks Eijiro's way with his Quirk and convinces him to join with the other students.

Sports Festival Arc
Eijiro participates in the Obstacle Race. He manages to finish the event, placing ninth, allowing him to participate in the next event, the Human Cavalry Battle. Eijiro teams up with Katsuki for the Human Cavalry Battle, saying that they will get Izuku's ten million points.

After the Human Cavalry Battle begins, Katsuki jumps into the air and tries to attack Izuku with Explosion, but Fumikage Tokoyami uses his Dark Shadow to block it. Hanta uses his Quirk to catch Katsuki so that he can land safely back on his team's formation, which Eijiro praises Hanta for. After Neito Monoma takes his headband without trouble and mocks him for always being attacked by villains every year, this made Katsuki enraged and tells Eijiro that their plans have changed; before they take Izuku's ten million points, they will defeat Neito's team. Katsuki battles against Neito, but Neito copies and uses Katsuki's Quirk against him. Katsuki tries to attack Neito again, but he copies and uses Eijiro's Quirk to block him and shrugs him off.

Eijiro then warns Katsuki not to attack on his own. After Katsuki grabs two of Neito's headbands and Hanta reels him back onto the formation, Eijiro states that they have placed high enough. However, Katsuki still wants more points and orders his team to attack; having Hanta use his Quirk, and Mina use her acid. Eijiro and his team ride on Mina's fluid to reach Neito's team faster thanks to Hanta reeling in his tape. Katsuki attacks Neito for the final time and grabs his last headband, which places their team at second place. Katsuki, however, wants to collect the ten million point headband and Eijiro goes with his team to where Izuku's and Shoto's teams are. Eijiro and his team reach their destination, but the Human Cavalry Battle ends before they could do anything. However, Katsuki's last minute actions allowed Eijiro and his team to reach second place, allowing them to participate in the final event.

The final event is a tournament event and Eijiro's first match is against Tetsutetsu. However, his fist fights Tetsutetsu to a draw, causing them to participate in an arm wrestling game to determine who will advance to the next round. After Katsuki defeats Ochaco Uraraka, Eijiro faces Tetsutetsu in their arm wrestling game to decide the tiebreaker. Eijiro manages to defeat Tetsutetsu in the arm wrestling game, thus allowing him to advance to the second round. Eijiro tells Tetsutetsu that it was a fine match.

Eijiro goes to sit down next to his class, noting that the match between Izuku and Shoto has begun. Eijiro tells Katsuki that he is next, to which Katsuki replies that he is going to beat him to death, causing Eijiro to jokingly comment that he'd like to see him try. Eijiro then states to Katsuki that both he and Shoto can send out lots of strong attacks without breaking a sweat, causing Katsuki to tell Eijiro that Quirks are physical functions. Like running too much causes you to run out of breath, Quirks have limits too.

Eijiro faces his opponent, Katsuki, in his second round match. During the match, both of them continuously hit strike one another, however, Katsuki is eventually able to wear him down with a flurry of explosions, rendering him unable to continue.

After the match between Fumikage and Katsuki ends, Eijiro comments on Fumikage's Quirk being weak to light.

Eijiro, along with his class, watches the closing ceremony of U.A.'s Sports Festival. He comments that Katsuki has been in a fury ever since he woke up after being knocked out at the end of his final match.

Field Training Arc
Two days after the Sports Festival, Eijiro is in class. During the Hero Informatics Period, Shota presents the pro hero nominations, which reveals that Eijiro received 68 pro hero nominations. Eijiro comments that the top two nominations are in reverse and Hanta replies that it is because the pro heroes seeing Katsuki in a straight jacket must have scared them off. After Tsuyu presents her hero name, Eijiro reveals his Hero name: Vigor Hero Red Riot. Midnight comments that his hero name is a nod to Crimson Riot. Eijiro replies to her that it is and, although it is retro, the hero image he is aiming for is similar to Crimson Riot. Midnight comments that since he will be carrying the name of a pro hero he looks up to, he will be hit with corresponding pressure, to which Eijiro states that he can handle.

After Class 1-A is finished formulating their hero names, Eijiro is given his personalized work place list in order to choose a work place that he wants to train at. Afterwards, Eijiro states that he wants to train at a work place that specializes in urban counter villainy.

On the day of the work place training, Eijiro is at the train station with his class so that he can travel to the work place of his choice by train.

Eijiro's workplace of choice is revealed to be Fourth Kind's hero office. At the office, Fourth Kind explains to Eijiro about his salary; that he receives it from the government. Suddenly, Eijiro sees that Tetsutetsu is in the office as well, surprising Eijiro. Eijiro greets Tetsutetsu with a hand shake. Fourth Kind decides to explain to Eijiro and Tetsutetsu what his office's practical operations are.

The workplace training comes to an end and Eijiro returns to U.A. In Class 1-A, Eijiro and Hanta laugh at Katsuki's new hairstyle, causing Katsuki to retaliate in anger.

After Foundational Hero Studies is finished, Eijiro is in the boys' locker room changing into his school uniform. He states that he needs to focus on his maneuverability.

End of Term Test Arc
One week before the end of term test, Eijiro notes that Momo Yaoyorozu is being virtuous, to which Katsuki angrily reminds him that he is also virtuous, saying that he will tutor him until he bleeds (since he has the third highest grade in the class). After Katsuki storms out of class, Eijiro says that it has been a while since he has seen Katsuki like that. On the day of the exercise test, Nedzu reveals that Class 1-A will be fighting the U.A. teachers in their exercise test.

Eijiro is paired with Rikido Sato and they must face Cementoss in their test exercise. The three of them arrive at their designated area where their test exercise will take place. Cementoss explains the 30-minute test; Rikido and Eijiro must either handcuff him or one of them must escape the battlefield within 30 minutes in order to win and pass the test. The test begins.

Eijiro and Rikido keep smashing their way through Cementoss's cement walls, but the more walls they destroy, the more walls Cementoss keeps creating to keep them at bay. Cementoss tells them that they are both too weak in battles of attrition and that they must push past their limits. They are unable to get past Cementoss's walls by the time the End of Term Test finishes and as a result, they fail.

Back in class at U.A., Eijiro is crestfallen that he is unable to go to the forest lodge due to failing the practical test. Izuku tries to cheer up those who failed, but Denki launches a comical tirade at Izuku. Soon, Aizawa enters the classroom and informs Class 1-A that all of them are going to the forest lodge which will be a boot camp, shocking Eijiro. However, Eijiro will be receiving harsher training at the boot camp for failing the practical test. Eijiro along with his class go to Kiyashi Ward Shopping Mall to buy necessities for the forest lodge. At the shopping mall, Eijiro sees that everyone has different needs and suggests splitting up for now and meeting up later.

School Trip Arc
The next day after the shopping trip, at U.A., Aizawa informs Class 1-A that the destination for their lodge trip has been changed and the new destination will only be announced on the day of the event. The first semester has come to a close and summer break has begun.

On the day of the event, Class 1-A boards a bus that will take them to the forest lodge destination. An hour later, Class 1-A's bus stops for a restroom break. However, Class 1-A notes that Class 1-B isn’t at the rest stop. Suddenly, two females wearing cat-like costumes and a small boy appear; the females excitedly introduce themselves as the professional hero team, the Pussycats. Mandalay explains to Class 1-A that they will be staying at the base of a mountain which is a part of their domain; they have three hours to reach the base of the mountain using their Quirks as they please and those who don't arrive there by 12:30 pm won't be served lunch. Soon, Class 1-A realize that they have already arrived at their destination and their training camp has already begun with the Pussycats being their supervisors. Some of Class 1-A try to leave, but Pixiebob uses her Quirk to create a landslide of dirt that causes Class 1-A to fall into a forest called Forest of Magic Beasts, which they must traverse to reach their destination. Suddenly, Class 1-A are confronted by a beast; Koji Koda tries using his Quirk to control the beast but it does not work due to the beast being made out of dirt. Izuku, Shoto, Tenya, and Katsuki mobilize and use their Quirks to destroy the dirt beast.

After Izuku, Tenya, Shoto, and Katsuki destroy the dirt beast, Class 1-A begins traversing the Forest of Magic Beasts. The journey through the forest to the Cabin takes around eight hours. Class 1-A arrive at the facility, battered and tired. It is now 5:20 pm in the evening. Pixiebob admits that she thought they would take longer to get to the facility; she praises Class 1-A for figuring out her Earth Beasts quickly and easily. Class 1-A fetch their luggage from the bus and put it in their rooms. Class 1-A go to the dining hall to have dinner. After finishing eating dinner, Class 1-A go to the hot springs. The next day at 5:30 AM, Class 1-A are outside the training camp cabin. Aizawa greets his students and tells them that they will undergo reinforcement training to strengthen and upgrade their Quirks which will also allow Class 1-A to obtain their temporary licenses.

Eijiro trains with his class. On the night of the third day, the League of Villains's Vanguard Action Squad attack the camp. During the attack, Eijiro is in the facility being protected by Blood King. A Dabi clone attacks the facility only for the threat to be dealt with quickly by Shota. Eijiro asks Aizawa to allow him to fight, but he orders him and the other students to stay in the facility. After the attack is over, the training camp ends and Eijiro returns home.

Two days later, Eijiro goes to the hospital to visit Izuku. Eijiro tells Izuku that they can save Katsuki thanks to a transmitter being planted on one of the villains by Momo and Yosetsu. Tenya deduces that Eijiro wants Momo to create a device for themselves so that Class 1-A can track down and rescue Katsuki themselves. Tenya demands that the rescue of Katsuki be left to the pro heroes, but Eijiro is tired of being unable to do anything that will make him a hero and a friend, causing them to get into an argument. After being calmed down by Denki and Tsuyu, although he fully aware that the matter should be dealt by professionals, Eijiro encourages Izuku to go through with the plan as it will allow him to reach and save Katsuki.

Most of Class 1-A are against the plan. After the doctor requests the class to leave, Eijiro tells Izuku that he and Shoto will be waiting outside the hospital tonight for him and Momo so that they can go and rescue Katsuki.

Hideout Raid Arc
Later that night, Shoto along Eijiro wait for Izuku and Momo. Izuku and Momo arrive but before Momo can speak, Tenya appears. Tenya is angry that they are about to repeat the same mistake he made at Hosu. Eijiro wonders what they are referring to but. Tenya punches Izuku in the face. Tenya is angry and frustrated that they are not taking his concerns, feelings and worry into consideration; Tenya says that he does not want to see Izuku or any of them land up with severe injuries. Shoto tells Tenya that they will not engage the villains in combat while Eijiro states that their rescue will be covert. Momo states that she came along to accompany them all in order to prevent them from engaging in combat. Izuku tells Tenya that after failing to save Katsuki at the training camp, his gut feeling is telling him that he must save Katsuki. Tenya sees that they are determined and resolute and is cheered up by the fact that they won’t engage in combat; Tenya decides to go with them.

Eijiro along with Izuku, Shoto, Tenya and Momo board a train to travel to a place called Kamino Ward, a place in Yokohama City in the Kanagawa Prefecture. At Kamino Ward, Izuku along with Shoto, Eijiro, Momo and Tenya put on disguises to make infiltration easier as well as to prevent the League of Villains from recognizing them. The disguised group exit the clothing shop and observe a video clip of U.A.'s public apology.

Eijiro along with Izuku, Shoto, Momo and Tenya continue towards the place that Momo's tracking device is detecting. After waiting for a while near the place, Momo notes that the villains have made no movements and states the possibility of Katsuki not being in the place while Tenya reminds them that if he sees any combat, then he will not hesitate to stop them. Izuku thanks Tenya and starts thinking about their options in "true Midoriya" fashion according to Eijiro and Momo. Afterwards, Momo, Tenya, Shoto, Eijiro and Izuku prepare to infiltrate the supposed League of Villains’ hideout.

Eijiro along with the group go to the back of the hideout and see a window. Eijiro stands on Tenya's shoulders to see what is inside. After Eijiro sees the inside with his night-vision goggles, he hands them over to Izuku. Izuku looks inside and sees that there are Nomus, confirming that the hideout is actually a warehouse. Suddenly, Mount Lady destroys the front of the warehouse which shocks Eijiro.

Seeing that the pro heroes are at the warehouse, Eijiro and the group assume that All Might is with Katsuki as they are speaking and the group decide to head home. Suddenly, the entire warehouse is completely destroyed by a man along with the surrounding area being significantly damaged. The man's aura above them utterly terrifies Izuku, Eijiro and Shoto.

As the battle between All Might, All For One, Katsuki and the League of Villains continue, Izuku comes up with an idea. Izuku says that the plan will not involve fighting and that it will enable them to rescue Katsuki and escape. However, the entire plan rests on Eijiro because Katsuki will respond to him due to the friendship they have built up during their time at U.A. Tenya understands that the plan is a gamble but considering the situation there won’t be much risk due to All Might’s presence.

Izuku puts his plan into action; Izuku and Tenya hold onto Eijiro with Izuku using One For All Full Cowl and Tenya using his Recipro Burst to burst through the wall while Eijiro uses his Hardening to protect himself, Izuku and Tenya. After Izuku, Tenya and Eijiro burst through the wall, Shoto creates an ice ramp; Izuku, Tenya, and Eijiro jump off Shoto’s ice ramp and head into the sky. All For One sees the trio and attempts to attack them, but All Might intervenes by punching All For One. Katsuki sees the trio while Eijiro yells at Katsuki to take his hand. Tomura tries to take Katsuki, but Katsuki uses his Explosion to launch himself towards Izuku, Tenya and Eijiro. Katsuki grabs Eijiro's hand and smiles.

Kenji and Spinner launch Mr. Compress into the air, but Mt. Lady intercepts him, allowing Izuku along with Eijiro, Tenya and the rescued Katsuki to get away. Izuku, Eijiro, Tenya and Katsuki land on the ground far from the battlefield and begin escaping.

Eijiro manages to escape to the front of the train station along with Izuku, Katsuki and Tenya. He and Katsuki converse, with Katsuki stating that he was not rescued and that he only escaped with them so that he wouldn't get in All Might's way while Eijiro is glad that Katsuki is safe.

After All Might defeats All For One, Eijiro along with Izuku, Tenya and Katsuki meet up with Momo and Shoto. They take Katsuki to a Police Station for his safety. Afterwards, Eijiro goes home.

Quirk and Abilities
Hardening (硬化): Eijiro's Quirk gives him the power to harden and sharpen any part of his body. The ability not only protects him from physical attacks, but also from heat and shock waves. The drawback to his Quirk is that there is a limit to how much damage the hardened skin can withstand and will cause the hardening to slowly dissipate.

Moves

 * Red Counter: While hardened, Eijiro endures a close-range attack with his skin, and then counters with a straight punch.
 * Red Riot Unbreakable: Eijiro reaches his maximum hardening level by turning his entire body extremely hard and rugged, leaving him with a monstrous appearance and practically invulnerable to most forms of attack. This form can only be maintained for around 30 to 40 seconds.
 * Red Gauntlet Eijiro rushes towards the enemy and delivers a single strong punch against them.

Enhanced Strength: While using his Quirk, Eijiro's physical strength appears to increase. He demonstrated it multiple times during the Sports Festival, first digging through several tons of metal scraps, then withstanding Katsuki's explosions without stumbling, which, according to the latter, was not due only to Eijiro's armor. In his arm-wrestling match against Tetsutetsu, his fingers dug through concrete and he eventually broke the surface the match was taking place on. He was also able to break multiple metal blades with a single elbow strike, as well as to destroy a wall with Izuku's help.

Enhanced Durability: Eijiro has enhanced durability thanks to his Quirk. His Hardening was able to withstand Katsuki's explosions for an extended amount of time and allowed him to emergence from the remnants of the huge faux villains that fell on top of him completely unscathed.

Battles
{{Scroll box|

Unforeseen Simulation Joint Arc

 * Katsuki Bakugo & Eijiro Kirishima vs. Villains: Win
 * Toshinori Yagi, Izuku Midoriya, Katsuki Bakugo, Shoto Todoroki & Eijiro Kirishima vs. League of Villains: Win

Sports Festival Arc

 * Team Bakugo vs. Team Monoma: Win
 * Eijiro Kirishima vs. Tetsutetsu Tetsutetsu: Draw, later won on the arm wrestling contest.
 * Eijiro Kirishima vs. Katsuki Bakugo: Lose

End of Term Test Arc

 * Eijiro Kirishima & Rikido Sato vs. Ken Ishiyama:Lose

Hero License Exam Arc

 * Denki Kaminari, Katsuki Bakugo & Eijiro Kirishima vs. Seiji Shishikura: Win}}

Denki Kaminari
Since they happened to be seated one behind another in class, they became good buddies and often make comments to each other.

Katsuki Bakugo
Despite differing personalities, Eijiro and Katsuki are on good terms with each other. Eijiro admires Katsuki, and despite his lone-wolf attitude toward him, he admires the fact that even though all the things he does may be a little too much, he still sees him as a very "manly" man and insists he assists Katsuki. Out of all of his relations, Katsuki's relation with Eijiro has the least conflict, suggesting that Katsuki views Eijiro as a friend. However, Eijiro can still become frustrated with Katsuki as seen when he complains that Katsuki is going too far in his fight with Izuku during the battle training class with All Might.

At the beginning of the cavalry battle ark when Katsuki makes a remark about the importance of winning, Eijiro is visibly moved by Katsuki's words and calls the other manly. During the cavalry battle, Eijiro approaches Katsuki in an attempt to form a team with him. Katsuki calls Eijiro "hedge-hog hair" at first but after Eijiro presents himself as rock who will not waver, the two form a team together with Ashido and Sero.

Over the series the relationship between the two improves greatly and Eijiro and Katsuki become close friends. While Eijiro is friends with a wide range of people in his class, he can constantly be seen talking to Katsuki and making an effort to include him in on activities while others would have ignored him. In one case, Eijiro invited Katsuki to go shopping with the class and in another he made attempts at conversation when the class results were handed out.

One of the most significant points in Eijiro's and Katsuki's relationship development was during Katsuki's kidnapping. After it was revealed that Katsuki was kidnapped, Eijiro was visibly distressed and immediately wanted to form a group and rescue him, even buying a pair of 50,000 yen night vision goggles in order to take back Katsuki from the villains. During this arc, Eijiro stated that ''"When I heard that they were after my buddy...I couldn't do anything!!" ''which confirms that he views Katsuki as a friend and was distraught upon hearing that Katsuki was kidnapped.

During the rescue, Izuku explains that only Eijiro can take Katsuki's hand and rescue him without Katsuki taking offense and refusing. This illustrates the intense and trusting connections that the two share and reveals that Eijiro and Katsuki are very close as Katsuki would not accept the help of any other person.

After this arc, Eijiro and Katsuki were more connected than previously, sticking close together during the hero license exam and hanging out together in free time. Often when Katsuki's whereabouts are unknown to the rest of class 1-A, they will ask Eijiro for an explanation.

While versing a particularly difficult villain, Eijiro thinks back to a time when he was voicing concerns about his powers to Denki and Katsuki. Katsuki speaks up and attempts to support Eijiro by talking about how strong he was. Eijiro seems to use this memory to motivate him and allows him to unlock his "unbreakable" state.

Similarly, when Eijiro is versing villains in the lair of The Eight Precepts of Death, he thinks back to Katsuki's words after he has failed to defeat a villain. This illustrates that Eijiro feels that he has failed Katsuki by not living up to his expectations. Eijiro obviously looks up to Katsuki and feels motivated by him but also feels disappointment when he cannot impress him.

Hanta Sero
Eijiro and Sero are good friends with each other.

Izuku Midoriya
Eijiro seems to be on good terms with Izuku. When 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. In more recent chapters, Ejiro and Izuku are shown to be on better terms than previously, often interacting in friendly ways.

Crimson Riot
Eijiro idolizes Crimson Riot and wants to become just like him.

Mina Ashido
Eijiro and Mina went to the same primary school together, and during their senior year of primary school, Eijiro became envious of Mina's hero abilities. Now while in high school, they appear to be on good terms despite not interacting much with each other.

Trivia

 * He is student No. 8 in Class 1-A.
 * He ranked 2nd during the Entrance Exam and 8th during the Quirk Apprehension Test.
 * His rankings in the Popularity Polls are as follows:
 * He ranked 15th in the First Popularity Poll.
 * He ranked 5th in the Second Popularity Poll.
 * His name contains the kanji for cut (切) and sharp (鋭).
 * He likes meat and manly things.
 * Horikoshi mentions that Eijiro was made to tie the class together with his personality.
 * He ranks 15th in Class 1-A's Grades.
 * Eijiro ranked in the Top 8 of the U.A. Sports Festival First-Year Stage.

Quotes

 * (To his classmates about Katsuki Bakugo's kidnapping) "When I heard that they were after my buddy...I couldn't do anything!! I didn't do anything!! If I don't act now...forget being a hero, I'm not even a man!"