Nagisa Shiota

Attendance number 11. The narrator of this work and the de facto protagonist. A boy with light blue hair styled like pigtails. He is recognized by himself and others as very passive and generally has a good-natured personality. Through the process of cornering and attempting to assassinate Koro-sensei, he develops his observational skills and constantly takes notes on Koro-sensei's characteristics and weaknesses. His biggest concern is his short height, and he wishes to "buy height" if he wins the prize money. He also has a feminine appearance that makes him look like a girl, to the point where even his female classmates see him as a girl, and when he cross-dresses, he becomes an attractive beauty that appeals to boys. However, his mental state is that of a boy, and he dislikes being treated like a girl. He is generally called by his first name by classmates and teachers, which is later revealed to be because his parents are divorced, and it was to ensure there would be no discomfort if he returned to his father's surname after separating from his mother.

His mother, Hiromi, imposes her distorted love on his way of life, career path, and appearance, but he does not hate her. When he saved her from danger, he expressed his true feelings and gained her approval for his career path through a conversation at the cultural festival. He maintains a good relationship with his father, who divorced his wife due to their marital discord. He was demoted to Class E due to poor grades, but more than that, he was abandoned by his former classmates and former homeroom teacher Ohno, who turned their backs on him, leaving him in despair as he was neither expected nor recognized by anyone. He harbors feelings of jealousy towards those who are recognized, despite his own self-deprecation. Initially, he envied Koro-sensei, who was both admired and feared, but after a failed suicide bombing attempt on Koro-sensei, his inferiority complex diminished. He has a habit of making spelling mistakes at crucial moments, but he ranked 6th in English in the first semester finals and 14th overall in the second semester finals.

His athletic and combat abilities are not high, but in the showdown proposed by Takaoka as a demonstration, he was chosen by Karasuma as a skilled student, took up a "real combat knife," and won with assassination skills that exceeded expectations. His talent for "concealing intent, approaching the target naturally," "intimidating the opponent with intent," and "not being intimidated in 'real' situations" proves his exceptional assassination skills. His slender and petite appearance gives a delicate impression, which helps him catch opponents off guard and showcase his talents. Lovro also highly evaluates his assassination skills and teaches him a special technique during the summer vacation, which he uses to win a revenge match against Takaoka. After experiencing the battle with "The Reaper" and his family circumstances, he becomes able to clearly sense "the wavelength of consciousness" and acquires skills like the Clap Stunner, one of The Reaper's skills, though not perfectly. He is initially confused by his many assassination talents and skills, but after protecting his mother from an assassin, he decides to use them "to protect someone." This decision, along with his newfound purpose for his assassination talents, leads him to seek a way to save Koro-sensei's life, apart from the assassination mission, with other students who also have doubts about the mission. During this process, he has a falling out with Karma, who had misunderstandings since before Class E, but they reconcile through a survival game and start calling each other by their first names.

For high school entrance exams, he applies to "Keisei University Affiliated High School," a highly competitive school. Although he initially gets a waitlist acceptance, he eventually gets in. Around this time, he also starts reconsidering his future career path after university, realizing through Sakura's words that he admired Koro-sensei as a "teacher." In his final meeting with Koro-sensei, he reveals his determination to become a teacher like Koro-sensei.

When he is detained by the government during the final assassination plan, he understands the true meaning of Karasuma's words and proposes to Class E what they should do next. After escaping, with Hiromi's approval, he participates in the final mission, showcasing his skills by using the Clap Stunner on Houjou. In the end, with everyone's consent, he personally delivers the final blow to Koro-sensei. Later, his divorced parents reconcile, and they regain their family life.

Seven years later, he becomes a student teacher at "Municipal Gokuraku High School," a delinquent school, but his height only grows to 160 cm, with little change in appearance except for cutting his hair. Initially underestimated by delinquents due to his appearance, he switches into a different mode when the boss says "I'll kill you," instantly getting behind the boss and pressing his middle finger to his throat, shocking the delinquents. The story ends with him using the skills he honed in Class E to pursue his path as a teacher. In "Graduation Album Time," it is revealed that he is hired at "Municipal Gokuraku High School" due to his achievements during his student teaching, and he is also scouted as a lecturer by Gakuhou.

In the live-action movie version, he is portrayed as a boy with short hair and timid behavior, with an added setting of having a childhood friend named Ayaka Saito in Class B.