Izumi is Mikan's father and the former moderating teacher of the Special Ability Class. His Alice was discovered when he was already an adult. He joined the Academy as a teacher at the age of 22, nineteen years before the main story takes place. The cause of his death remains unknown (it was rumored to be suicide, but the truth is revealed in Chapter 116; he was accidentally killed by Persona under orders from the Elementary School Principal). Yuka believed that someone working at the Academy murdered him. The High School Principal is actually Izumi's older brother and the one who inadvertently discovered Izumi's Alice through a photograph in their letter correspondence, using his own ability to detect other people's Alices either in person or through photos.
In contrast to his older brother's more serious demeanor, Izumi has a very cheerful and outgoing personality, traits inherited by Mikan. He often received scolding from Jinno-sensei. He was highly popular among the students. However, when provoked, he could be quite intimidating. Before coming to the Academy, Izumi was the leader of a motorcycle gang in his hometown.
Two years after joining the Academy, Izumi was informed by Jinno that he would be put in charge of the new Special Ability Class and its "special" students. Later, he was summoned by the Elementary School Principal, who told him that these new "special" students possessed dangerous abilities. Izumi never anticipated being asked to supervise and severely punish these special students. As the teacher with the Nullification Alice, this role was specifically designed for him, though he was deeply unhappy about it and strongly opposed it.
At times, Izumi can be a bit of a pervert. For instance, he wondered if he would be teaching high school girls and once proclaimed to Yuka, "I can see your panties clearly," when they first met and Yuka was trying to escape from the Academy.
