Iruka Umino

is an instructor at the Konoha Ninja Academy, and is characterized by the distinctive scar across his face which he has had since childhood.

Background
Iruka's parents were killed twelve years before the start of the series, defending Konoha from the Nine-Tailed Demon Fox. With his family gone, Iruka had no one to give him attention. Iruka thereafter became a prankster, trying to gain attention to stave off the loneliness. He would spend his time at the monument where his parents' names were engraved, and, in his darkest moments would be cheered up by the Third Hokage. Mizuki was a childhood friend of Iruka's after the Nine-Tails Attack, and usually made him feel better. It later turns out, due to other people giving Iruka more attention than they do to Mizuki, Mizuki's kindness to Iruka revealed to be an act just to gain the Hokage's approval, all the while making Iruka miserable discreetly.

Personality
Although he owes much of his miserable childhood to the Nine-Tails, he has no hostility towards its container, Naruto Uzumaki, and even cares for him as family. Early on in the series, he relates to Naruto's efforts to win the recognition of others through his antics; a tactic that he also used in his childhood to cope with his feelings of loneliness, which he can sense in the boy.

Because of this, Iruka goes out of his way to connect with Naruto outside the classroom- having realized that he could do more good as a mentor, than as a teacher. Iruka becomes even more aware of Naruto's situation when the Third Hokage asks him to contemplate living among people who would deny his very right to exist. Likely due to Iruka's more nurturing and compassionate nature, Naruto views him as a father-figure. The two enjoy their favorite ramen dish at the Ichiraku Ramen Bar whenever Naruto returns from a mission, where Iruka gets an opportunity to see how Naruto is developing as a ninja. Iruka's refusal to allow Naruto to graduate at first was not out of spite, but merely out of caring strictness and a desire for Naruto to work harder and reach his own potential.

Having known both loss and loneliness, he is sympathetic to others and instinctively tries to console others in times of grief or loss. Iruka is often the first person Naruto turns to when trying to understand issues of selflessness and honor. Iruka greatly admires both the Third Hokage and his beliefs. As a result, he regards the children of the village as the backbone of Konoha- even being willing to sacrifice his own life to ensure their safety.

Abilities
Little is known about Iruka's abilities. As a head instructor of the Ninja Academy, he is clearly proficient in all forms of basic ninja skills. According to the anime, Iruka shows some knowledge of genjutsu, as demonstrated when he posed as an enemy Rain ninja to test Sakura, and he also saw through genjutsu cast by Mizuki. During the Mizuki's Revenge arc, Iruka showed some skill in taijutsu as well, by keeping on equal footing with the now-improved Mizuki in his attacks. The anime showed Iruka using Sealed Bomb Square Release, which consists of setting an array of exploding tags and, once the target has entered the area, setting the tags to detonate if the target moves. While perhaps not as intelligent as Shikamaru or Kakashi, Iruka is known to be clever and able to assess situations carefully and quickly while under threat. Also, in the anime, Iruka seems to have an echolocation ability where he can get a sonar image of his surrounding area, perhaps playing on the meaning of his name, "dolphin."

Part I
When Naruto was desecrating the Hokage Monument with graffiti, Iruka yelled at him to get down and tied him up, berating him to focus on the upcoming graduating exams. While Naruto was supposed to transform into Iruka, he instead turned into a naked girl, which caused Iruka's nose to explode with blood, and earned Naruto a reprimanding. Iruka then punished Naruto to clean the Hokage Monument, but then invited him to Ichiraku Ramen Bar, where he learned of Naruto's desire to be Hokage.

Next day, when Naruto failed to perform three clones, Iruka failed him from graduating, ignoring Mizuki's false sympathetic request. Later, when Mizuki tricked Naruto into stealing the Scroll of Seals, Iruka came to his aid. Iruka protected Naruto from Mizuki's attacks and, after Naruto found out about the Nine-Tails within him, insisted that he didn't hate him. After the ordeal, he allowed Naruto to graduate from the Ninja Academy, due to the genin's newly acquired ability to create a high amount of advanced clones. From that point further, he makes sporadic appearances.

Chūnin Exam arc
He voiced concern about Team 7 being entered in the Chūnin Exams, such that, in the anime, he personally tested each member individually to see if they were ready by disguising himself as a Amegakure ninja. Once they passed the exam's second phase, he acted as a messenger that granted them access to the preliminaries.

Invasion of Konoha arc
During the invasion of Konoha, Iruka escorted his students to safety in the shelters behind the Hokage Monument- promising that he and the other instructors would protect them "even at the cost of our lives". He shared ominous looks with Konohamaru when the Third Hokage's representation cracked, and he comforted Konohamaru during the Third's funeral.

Search for Tsunade arc
He met Naruto at their favourite Ichiraku Ramen Bar to listen to Naruto telling about his adventure and later explained to Naruto that they have to do many missions to show other villages that they were still strong, even though their strength had been cut in half.

Mizuki Strikes Back arc
In the aftermath, Iruka was forced to suspend his teaching duties in order to go on missions and fill the void in personnel. In the anime, he was assisted by Pakkun to find Mizuki and go after Naruto and Tonton. When Iruka caught up, they send Tonton back to the village and Pakkun leads Naruto and Iruka to Shizune. Shizune led them in pursuing Mizuki, when they soon fell into a trap. Iruka then revealed that Shizune is not Shizune but Mizuki himself. While Naruto battles with Fūjin and Raijin, Iruka battles it out with Mizuki. Iruka wanted to bring the "old" Mizuki back, but Mizuki revealed that he was only nice to Iruka because he is Third Hokage's favorite. Mizuki led Iruka into a building used to test Ninja Academy instructors and battled there. After that, Naruto and Pakkun caught up with Iruka and they went to Mizuki's lover, Tsubaki. Tsubaki helped them reach Mizuki but it was too late. Mizuki has already drunk the formula and become stronger and monstrous. They battled again but Mizuki seems to have the upper edge. Iruka thinks of a plan to trap Mizuki, giving Naruto a chance to use Rasengan on Mizuki.

Ultimate Weapon arc
He later found time at the end of Part I to see Naruto off before he left the village to train with Jiraiya.

Rescue Gaara arc
Iruka met with Naruto when he returned two and a half years later, cheering him up after he found out that all of his friends had advanced in rank during his absence.

Invasion of Pain arc
After Jiraiya was killed, Iruka comforted Naruto, and told him that Jiraiya would always be proud of him. He went on to inform Naruto of how Jiraiya had always bragged about him, and had mentioned multiple times how he thought of Naruto as a grandson. Iruka also reminded him that he was now the one to carry on Jiraiya's legacy. During Pain's attack on Konoha, Iruka was found by one of Pain's bodies while attending to a wounded ninja. He refused to tell Pain where Naruto was, and was almost killed. Kakashi intervened, however, allowing Iruka a chance to get the ninja to the hospital and to later join a squad of Konoha ninja to help repel the invasion.

Following Pain's attack, Iruka was last seen apparently injured but alive, having been protected by one of Katsuyu's divisions. After Pain resurrected everyone he had killed, Iruka was seen standing along with the rest of the villagers. He thought back to the days when Naruto was at the academy, and compared it to the present while watching Naruto being cheered at by the whole village. After these memories, a proud smile spread on his face.

Other Media
Iruka is a playable character in the Naruto: Clash of Ninja series, appearing in four out of the series' ten games, although only the first two were released internationally.

He is also playable in Naruto: Ninja Destiny 2 (European Version) and Naruto Shippūden: Shinobi Retsuden 3.

Trivia

 * Despite having made very few appearances later on in the series, he has finished in the top five in every poll to date.
 * Iruka is one of five characters that have stayed in the Top Ten of every Character Popularity Poll.
 * In the first databook, Iruka's age was given as 25. In the second, it was listed as 23.
 * The name "Umino Iruka" can be taken as "umi no iruka" ("sea dolphin").
 * Iruka has black hair in the manga, but in the anime he is shown with brown hair.
 * Iruka shares similarities with Yashamaru:
 * Both were born in the same month
 * Both graduated to genin and chunin at the same ages: 11 and 16
 * Both lost family to the demons of their respective villages
 * Both became the first "precious person" to the respective jinchūriki of their villages
 * According to the Naruto Databook:
 * Iruka's favorite food is ramen from Ichiraku Ramen Bar, with his least favorite being ; a type of takikomi gohan, but with the ingredients added in various stages while cooking.
 * Iruka has completed 573 official missions in total: 288 D-rank, 183 C-rank, 90 B-rank, 12 A-rank, 0 S-rank.
 * Like the members of Konoha 11, he also changed his Forehead Protector from blue to black.

Quotes

 * (To Naruto)"Lord Jiraiya only had praise for you. He was always boasting about you, saying you were like his own grandchild. He had faith that you were the one who would inherit his will, and truly believed that you would one day be a great Hokage. Lord Jiraiya will always watch over you. Even this very minute, he's watching from somewhere. He wouldn't be happy seeing you sad like this. So.. Be your usual self, the one he praised so much. Don't stay depressed forever. For Lord Jiraiya himself, one of the Legendary Sannin...acknowledged you as his promising student!"