Aguri Yukimura

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

Appearance
Aguri has short black hair with bangs that go past her eyes, framing her face. She has a 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 cheerful, clear-minded, and 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.

History
Aguri was the older sister of 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, she 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 Aguri was meant to be his means of escape, but after saving her from Yanagisawa the God of Death befriended her and the two became close as the year went on. Aguri shared her troubles with him and kept him company and he helped her improve her teaching methods. When the order to kill the God of Death reached her ears, she 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 superior. As the building around her was being demolished by the now-omnipotent assassin, she 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, she used her last breath to convince the God of Death to not become a killing machine, instead advising him to become a teacher, continuing her teachings and to never let the students go.

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 Korosensei) "What a lovely feelers..! With these hands, I'm sure that you... will become a wonderful teacher..."
 * (To Kayano Kaede) "Well, at least, we have our black hair in common. Ahahaha..."