Iruka Umino

is an instructor at the Ninja Academy, characterized by the distinctive scar across his face that 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. His family gone, Iruka thereafter became a prankster, trying to gain attention and 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 close friend of Iruka back then and usually made him feel better, but eventually his intentions became an act just to get the Hokage's approval.

Personality
Although he owes his sad childhood to the demon fox, he has no hostility towards its container, Naruto Uzumaki. He can relate to Naruto's efforts to win recognition and the feeling that he is alone in the world. Because of this, Iruka goes to lengths to make Naruto happy even when the rest of Konoha ostracizes him. Naruto has since come to view Iruka as a father-figure, and will not allow anyone to harm him. 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.

Part I
When Mizuki tricks Naruto into stealing the Scroll of Sealing at the start of the series, Iruka comes to his aid. Iruka protects Naruto from Mizuki's attacks and, after Naruto finds out about the demon fox within him, insists that he doesn't hate him. After the ordeal he allows Naruto to graduate from the Ninja Academy, and from that point further makes sporadic appearances. He voices concern in Team 7 being entered in the Chunin Exams, such that in the anime he tests each member individually to see if they are ready by disguising himself as a Amegakure ninja. Once they pass the exam's second phase, he acts as messenger that grants them access to the preliminaries.

During the invasion of Konoha, Iruka escorts his students to safety behind the Hokage Monument. He shares ominous looks with Konohamaru with the Third Hokage's representation cracks and comforts him during the Third's funeral. In the aftermath, Iruka is forced to suspend his teaching duties in order to go on missions and fill the void in personnel. In the anime, he assists Naruto in capturing Mizuki when he escapes from jail. He later finds time at the end of Part I to see Naruto off before he leaves the village to train with Jiraiya.

Part II
Iruka meets with Naruto when he returns two-and-a-half years later, cheering him up after he finds out that all of his friends have advanced in rank during his absence. After Jiraiya is killed, Iruka comforts Naruto and tells him that Jiraiya will always be proud of him. He goes on inform Naruto of how Jiraiya always bragged about him, and mentioned multiple times how he thought of Naruto as a grandson. Iruka also reminds him that he is now the one to carry on Jiraiya's legacy. During Pain's attack on Konoha, Iruka is found by one of Pain's bodies while attending to a wounded ninja. He refuses to tell Pain where Naruto is and is almost killed. Kakashi intervenes, allowing Iruka a chance to get the ninja to the hospital.

Following Pain's attack, Iruka is last seen apparently injured but alive.

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 is proficient in Genujutsu as demonstrated when he posed as an enemy Rain ninja to test Sakura and also he saw through Genjutsu cast by Mizuki. During the Mizuki's Revenge arc Iruka showed some skill in Taijutsu also by keeping on equal footing with the now improved Mizuki in his attacks. The anime shows Iruka using Sealed Bomb Square Release, which consists of setting an array of exploding tags and, once the target has entered, 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.

Trivia

 * Despite having made very few appearances later on in the series, he still finished in the top five in every poll.
 * In the first databook, Iruka's age is given as 25. In the second, it is listed as 23.
 * The name "Umino Iruka" can be taken as "umi no iruka" ("sea dolphin").