Aguri Yukimura

Aguri Yukimura is the former teacher of Class 3-E and the late older sister of Akari Yukimura.

Appearance
Aguri has fair skin and short black hair with bangs that go past her brown eyes, framing her face. She also has a petite body except for her large bust, as it was shown when her sister felt some jealousy of her genes.

Aguri is known for her unusual fashion sense, as it was noted by the original God of Death and many other people, including her students from Class 3-E.

Personality
Aguri is shown to be a very cheerful and clear-minded person, who is truly passionate when it comes to teaching. As a teacher of Class 3-E, she is quite intelligent, being able to teach any subject in spite of chemistry being her first preference. She is also hard-working, having been essentially forced to work as a lab assistant to her abusive fiancé during night hours.

Aguri is also very empathic and perceptive, as when the original God of Death wondered why his apprentice betrayed him, she replied that his apprentice might have wanted his master to "see him", a perception later proved to be tragically prophetic.

Comically, Aguri is known for her odd sense of fashion which often leaves others dumbfounded. Despite that, she is remembered very highly by those who knew her and continues to make an impact in their lives.

History
Aguri was the older sister of the young acting prodigy, Akari Yukimura. Prior to the start of the series, Aguri held two jobs: one working as the teacher of Kunugigaoka Junior High School's Class 3-E during the day, and the other as the lab assistant for her fiance, Kotarō Yanagisawa.

One day, Aguri was assigned to be the caretaker of the recently captured master assassin, the God of Death, as none of the other lab assistants were willing to approach the assassin and she was treated as expendable or a "sacrificial lamb" as noted by Yanagisawa. Originally she was meant to be his means of escape, but after saving her from Yanagisawa and learn what 'compassion' was from her, the God of Death befriended her and the two became close as the year went on, to the point that he told her his true past, and Aguri shared her troubles with him. She kept him company and he helped her improve her teaching methods.

When the order to kill the God of Death reached her ears, Aguri decided to warn him of the impending danger and decided to help him escape. Despite this, he didn't listen and was about to use his newfound power to break himself out of the prison. She then tried to convince Yanagisawa to help the God of Death but instead met with a beating from her enraged work superior.

As the building around her was being demolished by the now-omnipotent assassin, Aguri witnessed her colleagues around her being killed by him and as a last resort to calm him down, she hugged the assassin from behind. However, she caught in the fire of the weapon set up by Yanagisawa and was mortally wounded. Because her wound was too severe to be healed, Aguri used her last breath to convince the God of Death to not become a genocide machine, instead advising him to become a teacher, continuing her teachings and to never let the students go.

Right before the monster leaves, her sister Akari witnessed the monster's departure, which caused her to mistakenly thought he was the culprit who killed her sister. Knowing that he will "taking over her sister's occupation" in Kunugigaoka Class 3-E, Akari arms herself with the tentacles, and infiltrates the school, thus the beginning of her "revenge", though this misconception would be eventually gone.

Legacy
Aguri's legacy is kept alive by her younger sister and Korosensei; both of who remember her and value her highly. She is remembered as a kind and cheerful woman loved teaching and always "saw" her students and did her best to encourage them. Though her life was cut short by her sacrifice to Korosensei, all thoughts about her are positive aside from Yanagisawa's opinions which are how he sees everyone else as an expendable.

Her legacy later become the answer for Korosensei who want know about being seen and seen by students. Not only her wishes become a path for redemption for Korosensei but he also able to depart with peace and love from the class that she was entrusted to him prior to her death.

For Akari herself, her pathway of revenge becomes abolished after she was defeated by Nagisa and Korosensei telling his past, realizing that Yanagisawa is the one behind the murder of her sister.

Akari Yukimura

 * Main article: Akari Yukimura

Aguri shared a close relationship with her sister and they love each other. Despite each other's busy schedule with Akari being an actress, and Aguri being a teacher in the day and a lab assistant in the night, they were still able to have their family time together. Aguri was very proud of Akari and sought to watch over her gently from the shadows as she made her way to adulthood. Their relationship was so close that Akari would playfully tease her elder sister and also advised her to end the relationship with Yanagisawa. Aguri's death had a great impact on Akari, to the point that she swore vengeance against Korosensei when Akari believed that Korosensei had killed her elder sister.

Korosensei
Korosensei first met Aguri back when he was human and the master assassin known as the God of Death who had become a guinea pig for Yanagisawa's antimatter experiment. When Yanagisawa needed people to observe Korosensei from a close distance, nobody dared to look after Korosensei since his reputation of being the infamous God of Death scared them. So Aguri was appointed by Yanagisawa to look after Korosensei.

Korosensei's first impression of Aguri was that she was his ticket to find a way out but was also annoyed by her bizarre fashion sense. However, as the year passed by, the two got to know each other to the point where the God of Death revealed his personal history to her, and Aguri stating her uphill battle to invigorate her demoralised students. The bond between them was so close that it was implied that Aguri grew to care for him and even have genuine feelings for the assassin. Her care for him led to her attempt to save him by warning that he will be put down following the explosion of the moon.

When Korosensei steadily turned into a monster in his escape attempt (causing Yanagisawa's lab to explode), Aguri held him down to calm his rage and anger, but is fatally wounded by a tentacle mine. Her last words to the assassin would inspire him to become a teacher and continue her work in restoring the confidence and self-esteem of Class 3-E.

Kōtaro Yanagisawa

 * Main article: Kōtaro Yanagisawa

Kōtaro Yanagisawa was Aguri's fiancee. Their marriage was arranged out of Yanagisawa's 'pity' and would get even worse. He only saw Aguri as nothing more than a servant and used this opportunity from his status as Aguri's husband to make her do whatever he said. He also had little to no consideration for her feelings as he commonly saw other women despite being engaged to her. It was shown that due to Yanagisawa's short temper, he often abused people whenever they annoyed him and Aguri, being his future wife, was not an exception. In turn Aguri, despite admiring his skills and intelligence, admitted that she couldn't bring herself to love Yanagisawa.

Quotes

 * (To Kayano Kaede) "Well, at least, we have our black hair in common. Ahahaha..."
 * (Her final wish to Koro-sensei) "If you have only one year left... If you would give your time... Go teach those children... They are lost in dark, just like you... Look at them straight in the eye... and I know you will find your answer."
 * (To Korosensei) "What lovely feelers..! With these hands, I'm sure that you... will become a wonderful teacher..."

Trivia

 * In season 1's premiere episode, Aguri was credited as "Female (Flashback)". She was in the God of Death's grasp while dying.
 * The scene was later remade as part of Korosensei's flashback in the 16th episode of the 2nd season.
 * There are known two times where she wore a plain cyan shirt instead of "lame shirts" in the lab.
 * Once the first God of Death immobilized Kotarō Yanagisawa.
 * Prior to her demise.