Iruka Umino is an instructor at the Ninja Academy, characterized by the distinctive scar across his face that he has had since childhood. The name “Umino Iruka” can be taken as “umi no iruka” (“sea dolphin”).

Twelve to thirteen years ago, the Nine-Tailed Demon Fox attacked Konoha, killing many people. Iruka’s parents were still out fighting the Fox and were killed. Iruka was dragged back for protection by an unknown ninja but wanted to stay where he was. After it was over, everyone in the Ninja Academy made fun of him and made him feel just like Naruto Uzumaki. He was always near the K.I.A. (Killed in Action) stone monument where his parents were listed and always cried. The Third Hokage would watch him and tried to cheer Iruka up. Mizuki was a close friend of Iruka back then and usually made him feel better, but he was just acting to get the Hokage’s approval.

Little is known about Iruka’s abilities, but he is clearly proficient in the basic ninjutsu and genjutsu, seen when he disguises himself as an enemy ninja and menaces Team 7 as a pretest for the Chunin Exam. The anime filler episodes show Iruka using Sealed Bomb Square Release (方爆法陣, Fūbaku Hojin), which consists of setting an array of exploding tags and, once the target has entered, setting the tags to detonate if the target moves. Because this only applies to the target, meaning others can freely enter the array without harm, it is possible that Iruka is skilled in this area.