|Alice Stone Color||
Izumi Yukihira (行平 泉水 Yukihira Izumi) was a teacher at Alice Academy and the father of the Mikan Sakura. He passed away before the series started, but he is remembered as the teacher with the same Nullification Alice as Mikan.
Izumi is the younger brother of the high school principal, Kazumi Yukihira. He was once the moderator of the Special Ability Class and was put in charge of taking care of Rei Serio, the boy who would grow up to become known as Persona. He was also formerly the homeroom teacher of Elementary B Class and later Elementary A Class.
As stated by Noda, Izumi had influenced the Academy greatly, encouraging the children to appreciate their Alices and themselves and to give them something to look forward to in life, considering how the Academy was stricter during his time. He brought a cheerful, lively mood to everyone, even allowing his students to call him Yukki (ユッキー). He was loved by almost the whole Academy.
Izumi was handsome and appealing seeing as he had a Yuki fanclub, which was composed of female students. He had short straight fair hair with bangs that covered his eyes, but changed it where his bangs parted in the middle when his brother said it was an old style and blue eyes.
Izumi had a cheerful, social, and kind personality that he passed down to his daughter. Izumi had a belief that all alices could be good, but it depends on how the user decides to use it. Izumi was very close to his students asking them to call him "Yukki", which differs greatly from Jinno's more professional and scary way. Although, once being a delinquent in his teenage years, Izumi was hotheaded at times, shown when he punished Anju L. Narumi by throwing him in the air. He was quite perverted, as he asked his brother if he was going to teach girls and commented to Yuka that he could see up her skirt when he first met her. Like Mikan Sakura, Izumi was naive and reckless, which got him bullied by Jinno and his brother for making stupid choices. Like Mikan, Izumi was very intimidating and had a temper when he was angered or provoked, as shown when he gave Yuka Azumi a murderous stare after she called him a pervert when they first met. Aside from his cheerful and easygoing nature, Izumi was known to have always acted in the best interest of his students and for a cause he believed was right, as he risked punishment for shielding Yuka from the Elementary Principal, he refused to be the moderator for the Dangerous Ability Class because of the students being used as weapons, and he didn’t blame Persona for his own death and harbored no ill will towards him.
Izumi had a normal life before coming to the academy. He never knew he even had an older brother until he was in his late teens, when Kazumi Yukihira began writing him letters from the academy and suggested that Izumi come to the academy due to that Kazumi was sent to the academy years before Izumi was born. Izumi came to the academy at age 22 and became a teacher, when his brother figured out that he had an Alice from their exchanging of letters. Before becoming a teacher, he was a rebel and the leader of a motorcycle gang. When they first met, Izumi was delighted, but Kazumi hit him and then welcomed him. Despite Kazumi's harsh treatment, he and Izumi immediately developed a strong sibling relationship and Kazumi took on the role as a parental figure to the easygoing Izumi. He was immediately embraced by his students for his cheerful and easygoing personality, even though it annoyed serious types of teachers, particularly Jinno, and his brother. The first person that caught his attention was Yuka Azumi, a student of his who tried to escape from the school. He stopped her and the two immediately disliked each other due to Yuka’s stubbornness and Izumi’s perverted attitude. However, he caught her after being electrocuted from the gates and comforted her as she broke down about her desire to see her family again. From then onward, they became "best friends", even though they still got on each other's nerves. Two years later, the Elementary Principal explained to Izumi that he would be the teacher of the Special Ability class. As Yuka became middle school student, Izumi hears rumors about her being the Elementary Principal’s lover and went to the middle school section to talk with her. Izumi found Yuka alone and crying, because of her Stealing Alice has been causing her trouble. He gave Yuka advice that she had a choice to use her Alice for good or bad. When he discovered that the Elementary Principal had been forcing Yuka to steal other people's Alices and was mistreating her, he saved her, despite being threatened by the Elementary Principal himself.
Izumi then had a problem with a ten-year-old Narumi, who had been using his alice irresponsibly and refused to cooperate with the students and teachers. Izumi decided to make Narumi and Yuka partners and they initially cooperated with each other until Narumi used his Pheromone Alice on her. Izumi went after Yuka, when she ran away from embarassment and gave her his Nullification Alice stone. This made Yuka give a loving expression and he felt awkward about it. This moment was witnessed by a fellow teacher who taunted him that Yuka was being bad. He dismissed it to her that it wasn’t what it looked like, but told himself that he could not be falling in love with a student. Two years later, he was forced to get a haircut because his brother said it was an old style, which made everyone laugh at his new hairstyle.
More than a year later, after the Elementary Principal proposed marriage to Yuka, she promptly confessed her love to Izumi, who, after getting over the initial shock, rejected Yuka's confession, not uttering a word, and left her alone and confused. Izumi saw Yuka again when she jumpedout the window of the Elementary Principal’s office, where she told him she would get stronger. Izumi finally acknowledged his feelings for Yuka and confessed that he loved Yuka in front of everyone at school. At first, she thought he was lying, but he assured her that he was being genuine and asked her to give all her pain to him and hugged her. This caused him to be beaten by from his brother and Jinno, who admonished him for having a scandalous relationship with a student. He admitted that he knew their relationship wad wrong but he promised to protect her and reaffirmed his commitment to Yuka. Albeit with great reluctance, Kazumi allowed Izumi and Yuka to continue their relationship, as he was soft with Izumi and had grown to like Yuka.
Afterwards, Izumi took Yuka to the Hime Hana Dungeon and introduced her to Rei Serio (who later becomes Persona), whom he had been caring for since Rei was abandoned by his parents as a small child. Izumi told her that his and Rei's dream was to have Rei leave the prison to see the world and form a family to love and accept Rei. Hearing this, Yuka putted Izumi's alice stone inside Rei, which made his rotted appearance better. This made both Rei and Izumi overjoyed, as this made them a step closer to their goal to have a family. Izumi and Yuka then went back to his room where they slept together. When he woke up, he received a phone call regarding"that thing" (Rei) had been released from his prison by the Elementary Principal. Yuka woke up and asked him what was wrong. Izumi kissed her and told her that he would come back soon and not to worry.
While walking to his location, Mikan, who was watching him while time traveling with Nodacchi, knew about his inevitable death and decided to confront him to prevent his death. She was convinced to let things be because alternating history would create a time paradox until she accidentally tripped and fell through the portal. Izumi asked who she was but Mikan was too speechless and scared to speak to him. She was returned to the portal by Tsubasa Ando, but not before Mikan yelled “Dad!!” before leaving and he sawher crying. He wondered who she was but subconsciously called her "Mikan".
Izumi arrived to the Elementary Principal’s office to find that Rei had been manipulated to by Elementary Principal into blaming Izumi for his confinement. Izumi tried to take Rei away, but he refused and began to use his Mark of Death Alice on him. Izumi attempted to explain to Rei why he wad locked up in that prison but Rei refused to listen to him and used his alice again. This time Izumi was unable to nullify these marks and he became so infected that he realized he was about to die. His last words to the Elementary Principal were “You... won't have your own way definitely...".  Before dying, he thought about how he broke his promise to Yuka about fulfilling her dreams of having a happy family and remembered Mikan calling him "Dad".
Despite the marks in Izumi’s body and the suspicious circumstances surrounding his death, his official cause of death was ruled a suicide. Upon seeing Izumi’s corpse, Kazumi was nearly overcome with grief and tried to prevent himself from shedding tears while he touched Izumi’s body. All the students deeply mourned Izumi and attended his funeral. Yuka would not find out about Izumi’s death until a few days later, when Kazumi finally told her. She would eventually discover the Elementary Principal manipulated a traumatized Rei into killing Izumi and she inserted Izumi and Rei’s Alice stones into the Elementary Principal to shrink his body to that of a child and make him lose a significant amount of his powers in retaliation. She then would discover she was pregnant with Izumi’s child, which deeply saddened her because, while she knew she would love the child, she would never have the happy family she wanted with Izumi.
When Yuka gave birth to Mikan, she imagined Izumi holding Mikan, happily announcing it was a girl, and told her she did a good job. However, Yuka would later choose to give up Mikan to protect her from the academy; this, along with other series of events, would provoke Yuka to join the Z Organization to seek revenge against the Elementary Principal for taking away everyone she ever loved.
Hana Hime Arc
While she battled Persona, Mikan allowed herself to get infected but she subconsciously used her Nullification Alice and Persona could see someone behind her. He recognized the person as Izumi, who smiled and told him not to hold on to hatred. This caused Persona to break his Alice Control Earrings and infect himself while suffering a breakdown.
When Yuka was killed by a bomb planted by Goshima under orders from the Elementary Principal, Yuka imagined Izumi carrying her in bridal style. She apologized to him for failing to protect Mikan but he assured her that she did the best she could. Her hair then got longer, and she and Izumi wore wedding attire.
At Yuka’s funeral, she was buried next to Izumi and her surname was changed to ‘Yukihira’. In a comical scene, Izumi, from inside a picture, told Shiki to stop Mikan from kissing Natsume Hyūga and called him a traitor when Shiki ignored him while Yuka tried to calm Izumi down.
Izumi has the Nullification Alice (無効化のアリス Mukōka no Alice) that was eventually passed down to his daughter, Mikan. This ability was also the reason he was assigned to look after Rei Serio, due to immunity from Rei's Mark of Death Alice. Izumi appeared to have full control over his Alice.
Main article: Yuka Azumi
Yuka was Izumi's former student in the Elementary School Division. She is Izumi's lover and the mother of Mikan Sakura. They first met each other when Yuka was trying to escape from the school but was stopped by Izumi. According to Noddachi,Yuka and Izumi were best friends, but there was no sign of "friendliness". He later defends her when the ESP forced her to steal other people's alices. Despite their 12 year age difference, they both fell in love and had a night together. After that, Izumi left her side to see Rei Serio, and tragically, died because of the ESP's manipulation over Rei. His last thoughts were of Yuka as he died and apologized mentally for leaving her. Mikan is their only daughter and was born after his death. Izumi wanted to fulfill Yuka's dream of having a family, since hers abandoned her and felt guilty that he was unable to fulfill her dream when he died.
Main article: Kazumi Yukihira
Kazumi (or Kazu) is Izumi's elder brother and his only family in the academy. He accidentally saw his photo and realized that he was an Alice, thus making them to know each other through writing letters. Despite of their 18 years of age gap, Kazumi still doted and loved Izumi a lot. According to Izumi himself (mentioned by Nodachi during Time Travel Arc), the High School Principal is a brother, a parent, a boss, and also is someone that he was grateful to. He also said that the HSP is his idol and his loved one, making the HSP doted and love him a lot. However in Chapter 109, Izumi mentioned that Kazumi was still being formal with him, although it was almost 6 years since they met each other, with Kazumi ordering Izumi to call him by name rather than "brother". When he died, Kazumi felt guilty to him as he remembered his earlier conversation with Izumi, which Kazumi said it would have been better if Izumi died.
Main article: Mikan Sakura
Mikan Sakura is the only child and daughter of Yuka Azumi and Izumi Yukihira, and also Kazumi's only niece. She was born long after Izumi died and was raised by Yuka with the aid of Kaoru for 8 months until being left with her adoptive grandfather. He didn't know Yuka was pregnant at the time of his death (neither did she). However, he was the one who came up with naming her if their child turned out to be a girl. He accidentally met her during the Time Travel Arc in Chapter 115, who fell from the time window. When he asked her who she was, Mikan was unable to talk to him. However, as she was taken back by Tsubasa and was about to disappear, she called him 'Daddy'. Izumi seemed to realize that Mikan was his daughter as he called her name, 'Mikan'. If he had still been alive, it seems he would have had a father-daughter complex with her, as seen in chapter 144, when she and Natsume kissed, he yelled at Shiki to stop them from a picture.
Main article: Jinno
Jinno is the Math teacher and the head supervisor of the Elementary School Division. He was serving under the circumstance of Kazu Yukihira, even before the current story took place. He always scolding Izumi and hit him for various reasons, usually when Izumi did some mistakes like bringing a student (Yuka Azumi) with a ladder and for beating up Narumi. However, he also seems to be concerned about Izumi and worries about him as he said to him that the ESP tried to expel him from the school several times, but could not do it since his brother Kazu stood up for him. When Jinno found Izumi's corpse, he was visibly saddened and angered, saying Izumi was a fool with his hands clenched tightly and regret clear in his voice.
Main article: Rei Serio
Rei, now Persona is the moderator for Dangerous Ability Class. During the Flashback Arc, Izumi was assign to take care of Rei who was unable to control his alice, because of Izumi's Nullification Alice. He kept on training Serio and also wished that one day, Serio would be able to go to the outside world. However, Serio accidentally killed Izumi under the influence of ESP. He felt guilty for killing Izumi, and he carried the sadness and guilty feeling until he was adult. However, Izumi never blamed Rei for his death and thought of Yuka as he died.
- The name Izumi means "fountain, spring".
- Izumi's surname Yukihira is written as 行平, can be interpreted in 2 ways. If it is written separately into 2 characters, it means 行future + 平even/flat. However, looking at them as in one word, it means 行f平 a Japanese pot.
- Throughout the past story (until the current story), Izumi was the only one who bravely fought face-to-face against the ESP. Unlike him, Kazumi Yukihira (Izumi's brother), did not want to fight the ESP.
- Izumi's death has given big impact to many people. His death had caused people who are close to him to live in sadness and regret and trying to fight against the ESP. His death is also one of the reasons why Kazumi Yukihira, Yuka Azumi, Jinno, Anju L. Narumi, Shūichi Sakurano and Subaru Imai are trying to get Mikan Sakura out of the academy.
- In the anime, even though Izumi was never mentioned, it was implied that Yuka Azumi had the Nullification Alice, instead of Izumi, as it was passed down to Mikan Sakura and when anyone would mention her Alice they would say, "The same Alice as 'that person'" who was Yuka.
- Under Japanese age of consent law, Izumi would have had been arrested for engaging in sexual relations with Yuka Azumi.
- Tokyo's age of consent for Female minors is 18, while National age of consent is 13; however, regional laws on age of consent and sexual relations supercedes the national laws.
- Gakuen Alice Volume 20, Chapter 116, Page 11-12