Nagisa Shiota

Nagisa Shiota is a student in Korosensei's Class 3-E of Kunugigaoka Junior High School and the protagonist and main narrator of Assassination Classroom. He is also the one who ultimately assassinated Korosensei.

Seven years later, he becomes the adviser of Paradise High School Class 3-5.

Appearance
Nagisa is a petite framed boy with light blue hair and azure eyes. His hair goes past his shoulders due to his mother forcing him to keep it that way. He kept it in a pony tail until Kaede Kayano joined the classroom and put it in two pigtails. He is known for his androgynous appearance which has often been poked fun at by many people - most notably, Rio Nakamura and Karma Akabane.

Seven years after graduation, his hair is noticeably shorter and no longer tied in pigtails, though he still keeps his bangs.

Personality
Nagisa is a calm, collected, and friendly individual. He is exceptionally observant and circumspect of his surroundings and the situations that develop around him. He tends to pay strict attention to Korosensei in hopes to understand the motives of this mysterious being and compiles the information he has gathered in his notes for reference.

Despite his calm demeanor, he harbors deep insecurity about his talents and how he is perceived by the people around him. This is reflected by lack of goals and general pessimism about his own future. Nagisa also isn't easily fazed by things that would unnerve the average person as shown with his interactions with Karma and the prospect of using a real knife.

History
Nagisa is the son of Hiromi Shiota and her (presumably ex) husband. His mother had hoped for a daughter so she could experience all the things she had missed as a child through her, but got a son instead. As a result, she dictated his life from forcing him to keep his hair long, to being forced to crossdress and verbally abused him whenever he spoke against her. Her personality also caused her husband to leave her and Nagisa.

He was revealed to formally have been in Class D during his first two years of middle school before falling into Class E due to poor grades.undefined During those two years he hung out with fellow classmate Karma Akabane though they slowly drifted apart. Soon after starting the new term as a Class E student, Nagisa met Kaede Kayano. She gave him what would become his signature pigtails instead of the ponytail he usually uses to keep his long hair from being less noticeable, thus beginning their friendship.

Introduction: Assassination Time
As the narrator and main protagonist of the series, Nagisa is the student that is given the most screen time out of all his classmates. Introduced in Chapter 1, after homeroom is started by Korosensei, Nagisa gives the command for the class to stand. They all draw their guns, aim and fire at Korosensei while he takes the register. Nagisa listens to the creature lecture the class on their supposedly simplistic plan and demonstrates the effect the special bullets have on him if hit, much to Nagisa's astonishment. Nagisa, along with the rest of class 3-E tidy up the classroom under Korosensei's instructions.

When Kaede Kayano whispers to him pointing out the permanent crescent moon in the sky, Nagisa remembers the destruction of the moon and the meeting and introduction of the culprit. This happened along with Karasuma from the Ministry of Defense both explaining and actively showing what their future jobs will be, along with revealing the 10 billion yen reward.

Later, while thinking about how the students of Class E are not normal students, Terasaka, Yoshida and Muramatsu approach him about working on an assassination plan, which he agrees to do with them. After the trio left, Korosensei appears beside him with a rocket, which he says that snagged off an attack from Japan's Self Defense force when he wa returning. Nagisa asks Korosensei if it was troublesome being a target, but the latter says that it instead proves that he is indeed very powerful.

Upon this, Nagisa is reminded that he himself is the opposite - nobody would fear or acknowledge him. He figures that Korosensei might not even acknowledge him as a hitman, and that if he succeeded in the assassination, he can be acknowledged, somehow. He affirms that he has to succeed, by any means necessary.

When Korosensei is seemingly less alert Nagisa attempts to strike him with an anti-sensei knife. Korosensei blocks it as expected, but it turns out to be a feint as Nagisa throws himself onto his teacher with a grenade around his neck. Terasaka detonates it via remote and the plan seems to have succeeded. However Nagisa had been covered by Korosensei's shedded skin while the target escaped the blast. Initially extremely angry that Terasaka and his friends had pulled such a stunt and not caring about their classmate's welfare, Korosensei nevertheless praises how Nagisa had approached him in such an innocent manner but hiding his real motives. Nagisa then thought that this teacher might just accept their killing intent. This assassination attempt will be a large focal point behind Nagisa's abilities - mainly his ability to hide his bloodlust.

Helping friends and new additions
For most of the series Nagisa would act in a supporting role to classmates that receive a spotlight in various chapters such as his two friends Tomohito Sugino and Karma Akabane, or other classmates he gets along well with such as helping Maehara get revenge on a selfish female student and saving Yukiko Kanzaki from rogue high school students. Simultaneously he would observe and note down Korosensei's various weaknesses and habits to assist his classmates in further assassination attempts, some of which do actually come in handy such as Korosensei's fear of water.

After a school assembly Nagisa hangs back from the class, wanting to get a drink. However he is accosted by two of his former classmates. They attempt to remind and enforce the unofficial rules and customs imposed on Class E to Nagisa. When Nagisa remains silent, one grabs him by the shirt and threatens to kill him. At this Nagisa coldy chuckles and calls their bluff, scaring them off. This is witnessed by Korosensei and Karasuma, but also by the principal, who sees this as a minor threat to the school's status quo.

Nagisa and the rest of the class also saw the separate arrival of three assassins, each failing in their attempt to kill Korosensei. One being their new English teacher Irina Jelavic, and the other two being so-called transfer students - an A.I. nicknamed Ritsu by the class, and Itona Horibe accompanied by his mysterious guardian named Shiro. While the first two failed their task, Itona's near-success (due largely to being implanted with the same tentacles as Korosensei) brings home the possibility to Nagisa and the class that should someone else other than the students succeed, they would go back to being misfits and nobodies with no goal or purpose. At this they resolve to improve themselves so that they are the ones that will kill their teacher to save the world.

Talent time
Two months since Korosensei's arrival, Class E's PE teacher Tadaomi Karasuma initially had the impression that Nagisa was an average student. However, during training, he felt a strange presence coming from behind, similar to that of snakes. He parried the attack only to realise that the 'snake' turned out to be Nagisa. When Akira Takaoka arrives at Kunagigaoka in order to train the Class E students better against Korosensei, Takaoka's brutal methods forces Karasuma to intervene. He challenges Karasuma to choose one student to attempt to assassinate him, using a real knife.

Karasuma decides to choose Nagisa based on the presence he had felt earlier from the boy. Although Karasuma does not force Nagisa to fight, Nagisa trusts his teacher's decision and does so, in part due to the fact that Takaoka had injured Maehara and Kanzaki earlier. Realising that he only needs to kill Takaoka to win, Nagisa calmly walks up to his opponent with a smile, close enough to whip the knife at Takaoka's throat in close range. The intent to kill catches Takaoka off guard and causes him to lose his balance. Nagisa grabs Takaoka's shirt to pull him to the ground and swings around to the back, covering Takaoka's eyes with one hand and with the other holds up the back end of the knife at the throat. The teachers and the class are stunned at this result, with Karasuma realising that Nagisa does indeed have the talent and ability to hide his bloodlust for assassination. Nagisa's victory resulted in Takaoka receiving the sack from the principal himself, Karasuma getting his job back and an increase in respect from his classmates.

Assassination Island Arc
After Class E won a wager against Class A in the end-of-semester exams, they journeyed to an island resort in Okinawa for the summer vacation. It was also the place where they planned to kill Korosensei. Nagisa contributed to the attempt by scouting underwater for the best places to hold the attempt and later helped create a hydraulic water cage to trap Korosensei. Despite the class's best efforts, their plan ultimately failed when their teacher resorted to his last resort - transforming himself into his absolute defense form, a sphere with an invincible crystal barrier surrounding him. However in this form he cannot move.

Later that night, half of the class succumbed to poison. Nagisa was among the other half unaffected. The mastermind behind it called Karasuma and would hold them to ransom. Claiming to have the antidote to the poison, he demanded to have Nagisa and Kayano come up to the mountaintop hotel with the helpless Korosensei within the hour. Everyone knew that the two would be held hostage if they followed through with his demands, so the standing students as well as the teachers infiltrated the heavily guarded hotel with Ritsu's aid to steal the antidote. The heavy guard presence forced Irina to separate from them and act as a distraction, while Karasuma was incapacitated by a paralyzing gas in downing the professional hit man Smog. Nagisa was given the duty of holding Korosensei and at one point swivelled him around when the latter carelessly mentioned that this was a summer vacation, much to the class's anger. In Chapter 66 Nagisa accompanied the girls through a crowded bar in case they needed a guy to distract any guards, though to his dismay he was forced to cross-dress to avoid any suspicions. To add further misery, Nagisa was approached by a rich boy named Yuji Norita, and was forced to put up with him while the girls continued their plan. In the end, the girls used Yuji's unfortunate accident with another patron to distract the guard, leaving Nagisa bemused that he had to cross-dress for nothing.

The class finally manage to reach the top floor and discover the mastermind to be Takaoka, who wanted revenge against Class E for the humiliation he suffered when he returned to the Ministry of Defense. He swore vengeance against Nagisa in particular ever since his loss to him and claimed that Nagisa's smile was the source of his nightmares. Takaoka led Nagisa and the class to the helipad and beckoned Nagisa to fight him again. Nagisa complied and attempted to reason with Takaoka to no avail. Instead, he blew up the antidote, triggering Nagisa's bloodlust and intent to kill in his despair. However, Terasaka knocked him out of it using his thrown stun rod before collapsing from the poison. Nagisa and Takaoka then fight, but the latter's combat skills and increased awareness initially overwhelms the boy, making even Korosensei worried about the potential outcome. Despite being badly beaten, Nagisa revealed to have one trick up his sleeve, a technique he learnt from Irina's mentor Lovro before the class left for the island resort. By making Takaoka concentrate on Nagisa's knife, Nagisa lets it fall before faking him out with a sudden loud clap. The sudden fake out surprises Takaoka enough for Nagisa to retrieve the stun rod and shock Takaoka into submission. Takaoka collapses to his knees and Nagisa points the stun rod at his throat. Despite the former's cruel actions, Nagisa thanked him with his trademark smile for teaching him bloodlust as well as the importance of friends in controlling said bloodlust before striking him unconscious.

With the incident behind them, Nagisa thanked Terasaka for snapping him out of his moment of madness. Terasaka shrugs it off, stating that if Nagisa died or was at least incapacitated permanently, it would be one less helper to kill Korosensei. As the ill students recovered, the exhausted class spent the rest of their resort time relaxing. Before leaving Korosensei (who returned to his normal form following Karasuma's failed attempt to seal him with concrete), created the Assassination Test of Courage, a trial supposed to scare the students in pairs with the idea of drawing them closer together but the students saw through his ulterior motive to create love gossips. Nagisa was paired with Kayano, though the latter still felt the physical injuries from the fight with Takaoka.

Early Activities
The start of the second semester was eventful as Kotaro Takebayashi briefly left Class E and went back to the main school campus with Class A. When the class confronted him after the end of the first day, Takebayashi cited personal reasons despite the bounty to kill Korosensei rising to thirty billion yen if a group took him down. Nagisa attempted to stop him but was held back by Kanzaki, who was well aware of and understood Takebayashi's intentions. Nevertheless, Nagisa and other Class E students tailed their former classmate to ensure that he was alright and settling down comfortably. Takebayashi later had a change of heart and discovered his motivation to kill, thus returning to Class E after destroying one of the principal's prized items.

To increase the intensity of their training, Karasuma started teaching the class 'free-running', a skill where any person can use their mobility to quickly reach a goal point regardless of any obstacles. Korosensei would soon put the students's new skills to the test by playing a game of cops and robbers, where the teachers would try to catch the escaping students in a one hour time limit. Nagisa's group was forced to free their classmates early on due to Karasuma's inhuman abilities in catching them, using any method to make Korosensei turn a blind eye. The students won when Kataoka, Okano, Maehara and Mimura (as the fastest students) lured Karasuma away from the school, allowing Nagisa and his group to submerge themselves in the pool to prevent Korosensei (known for his weakness to water) from capturing them in the last minute.

After this, Shiro and Itona made their third attempt on Korosensei after framing him for actions he did not commit. Itona's failure however leads to Shiro abandoning the boy, leaving the class to take care of Itona who finally joins the class. Later, Nagisa and the boys were led by Yuma Isogai in a fierce game of boutaoshi against Class A led by Gakushu Asano. Class E's Hannibal-like tactics and Isogai's leadership were able to outwit Asano's command despite the backing of four physically intimidating Western students and their goal of crushing their opponents instead, and this allowed Class E to gain the win.

Mistake and Nursery Time
As the mid-term exams were approaching in two weeks time, the class barely have time to train. To study and train at the same time, some of the students including Nagisa began free-running from the mountain school to the city using the trees and rooftops. However this gets them into trouble after surprising an old man and breaking his leg, which greatly angers Korosensei enough to slap them in their faces. To teach them a lesson (and not exactly a punishment) Korosensei forbids ALL of Class E to study for the mid-terms and force them to help out the injured old man. The class helps out at Wakaba Park's Nursery where the old man runs the place. While most look after the kids or rebuild the run-down building, Nagisa takes care of a young abusive girl named Sakura who is the oldest of the kids and of elementary school age. Initially having trouble connecting with her, he soon learns that Sakura is constantly bullied on by her classmates, and thus her high rate of absenteeism causes her to fall behind in her studies. Nagisa helps her with the basic maths, and also teaches her how to deal with the bullying problems. After two weeks Sakura comes back from her school happily exclaiming to a very pleased Nagisa that she came first in the maths test, adding that her surprising presence distracted her bullying classmates from concentrating properly. It was this more than the class's reconstruction work that the old man forgives the class and allows them to return back to their school. Those two weeks without being able to study costed the students greatly, with everyone except for Karma dropping in rank from the first semester exams.

The God of Death Arc
Nagisa and other students run into a young male florist, who earlier witnessed the old man's fall. While the florist charms everyone, Nagisa feels oddly at ease with him. When Irina is suspiciously absent from the school following Class E's failed attempt to romantically hook her up with Karasuma, the florist shows up unexpectedly and reveals to have kidnapped her. He identifies himself as the God of Death, demands for all of the students to come to a secluded warehouse that night where Irina is held hostage and not tell Korosensei or Karasuma. Using the special gym suits they were given by the Ministry of Defense, the students arrive at the warehouse. Before entering however, Nagisa asks his fellow peers permission to perform the clap stun technique (the same one he used against Takaoka) should their rescue plan come undone. He brought along a real knife to show the seriousness of the situation. Thinking that the hit man would recognise the technique, Nagisa proposed that he would perform the technique as a distraction while everyone else would attack when their target is too focused on Nagisa.

After entering the warehouse, the God of Death had trapped the class in a makeshift prison to use as hostages, However the class was prepared for this and made their escape. The class was then divided into three teams based on combat, rescue and reconnaissance, with Nagisa placed into the battle team. Soon after separating however, the God of Death appears before the battle team and quickly takes out Kayano. Seeing how fast the hit man is and with victory highly unlikely, Nagisa attempted the clap stun technique. The hit man did recognise what the boy was up to and immediately performed the technique on Nagisa first. The difference in ability and skill paralysed Nagisa and would fall unconscious, though not before witnessing the whole team get annihilated and listening to the hit man explaining about the wavelength of a person's consciousness. After that point, Nagisa is too dazed and paralysed from the God of Death's attack to play a further role in the arc though has recovered enough to witness Karasuma eventually defeat the hit man.

A Time for Revolution - Nagisa's Time
When Korosensei holds a career consultation for the class, Nagisa seems unable to decide on a suitable career. Before being interviewed, Nagisa silently removes a size label from Irina's newly bought clothes without her noticing, which the class notices. Speaking with Korosensei, he tells him that he may have the talent for assassination, being able to discern people's intentions and expressions with ease, further amplified after receiving the God of Death's clap stun attack. Korosensei, however, saw through Nagisa and reminds him that his assassination talent has only flourished due to his bravery, which is unfortunately fueled by desperation, noting that Nagisa had no thoughts about what happens to himself. Korosensei agrees that Nagisa has the talent (but not the discipline) and will support him as his teacher should Nagisa wish to pursue this path despite the dangers.

When Nagisa returns home, his mother Hiromi speaks about her plan to have Nagisa return to the main campus as soon as possible. Nagisa immediately disagrees and begins state his case until he senses a quick change in his mother's mood. She lashes out at him for not wanting to follow the path she laid out for Nagisa and the boy knew that further discussion would provoke her even more. Nagisa grows even more anxious when Hiromi intends to talk to his homeroom teacher the next day.

The topic of Nagisa's mother opens up in class, and Sugino notes that Nagisa's mother would react negatively to him and Karma playing at Nagisa's house. With Karasuma out on a business trip and Irina sorely lacking the maturity to answer questions in a mock interview session, Korosensei disguises himself as Karasuma to avoid suspicion.

The meeting initially goes well until the topic of mother and child looking alike arises. Hiromi begins obsessing over Nagisa, revealing her inferior complex and control-freak nature as she prevents Nagisa from speaking all the while trying to convince Korosensei to let Nagisa return to the main campus. Korosensei, seeing how Hiromi treats her own son, finally understands how Nagisa came to be the person he is now and refuses, citing Hiromi's inferiority complex and Nagisa's lack of assertiveness/independence as his reasons. He tries to counter Hiromi that Nagisa should control his own life and is not a tool for her to hide behind. Hiromi's temper erupts instead, shocking the whole class eavesdropping outside. Hiromi leaves in a rage, swearing that she will show the truth to Nagisa. Korosensei admits that he said too much, but tells Nagisa that he should take control of his own life. Nagisa ponders over this.

Nagisa returns home finding his mother in an uncharastically good mood but is drugged to sleep during dinner. He wakes up at night in front of the Class E building with Hiromi standing with a fire torch in hand. Hiromi wants Nagisa to burn the place down with his own hands so that his guilt will prevent him from returning, but he refuses. Suddenly, a hidden assassin who was targeting Korosensei disarms Hiromi of the fire torch with a whip but Nagisa stands up to him. Declaring that he wants to have a different life even if it means "graduating from his mother", Nagisa defeats the assassin with a weaker version of the clap stun technique before Korosensei arrives. While Korosensei drives Nagisa and his exhausted mother back home, Nagisa decides to use his talent to save and help people rather than for assassination, something that his teacher agrees to. The next morning Nagisa begins easing his mother's burdens, with him starting to cook breakfast, do chores and go into a respectful high school, but on the condition that she let Nagisa stay in Class E. Hiromi begrudgingly agrees.

School Festival and Final Exam
When the school hosts its annual festival, Class E is disadvantaged in attracting customers due to its mountain location one kilometre away from the main campus. Nagisa performs the role of waiter as the class tries to sell its acorn noodles specialty, using the natural ingredients of the mountain against Class A's sponsored cafe. Thanks to Nagisa's continued tutoring of Sakura and the kids from the nursery, they were among the first to arrive to Class E's restaurant. However Nagisa was surprised to see Yuji Norita from the Okinawa summer vacation to track him down. Forced to cross-dress again (this time by Rio Nakamura) to get more money, Nagisa gives Yuji hospitality but the latter becomes increasingly suspicious as more questionable characters (such as Lovro and Red Eye) arrive at the restaurant (invited by Korosensei). Yuji eventually figures out that Nagisa is lying thanks to a skill he did not want to pick up. Nagisa teaches him that he can turn his weaknesses into strength and also reveals that he is male, to Yuji's shock. Seemingly depressed he refuses Nagisa's attempt to refund him and walks away.

The next day the class finds their store lined up with customers, and Ritsu finds out that Yuji was behind this, having advertised the class's menu on his blog as a famous food critic. Yuji's actions would keep the Nagisa and the class busy until they ran out of acorn noodles to sell, thereby having to close the store early and sacrifice the chance of beating Class A. Afterwards Nagisa is surprised by the visit of his mother Hiromi, who makes it up to him and allows him to stay in Class E. She also pleads that he stays with her until he becomes an adult, which Nagisa happily agrees to. The festival ended with Class A making the most money though many note that the result could have been different had Class E (who came in third overall) continued to fight to the end.

In preparation the second finals exams, Gakushu Asano asks Class E to kill his father's education philosophy by monopolising the top 50 spots, and give Class A being taught by the principal himself a decisive defeat. Nagisa, being one of the two best Class E students in English, helps tutor his classmates in the subject. When the exams arrive even Nagisa had trouble solving the questions during the English exam. Despite the harsh difficulty of the exams set by the principal, the efforts of Nagisa and the class rewarded them all with the top 50 spots, thereby beating Class A decisively.

End of the Semester: Truths and Revelations
The end of the second semester takes a dangerous twist as Kaede Kayano launches a surprise attack on Korosensei. She reveals to have implanted tentacles upon herself and hid her massive bloodlust by making Nagisa more noticeable, as well as stating that she is the sister of Aguri Yukimura (Class E's former teacher). The next day, she attempts to assassinate Korosensei once more but the power of the tentacles was gradually consuming her which will kill her. When Korosensei asks the class to find a way to distract Kayano, Nagisa is unable to believe that everything his friend had done for the whole year was all an act. He walks up to her calmly and negates her bloodlust with his own by kissing her. The act surprises Kayano and shocks her into unconsciousness, giving Korosensei enough time to remove the tentacles from her neck.

Seeing that the situation has changed, Korosensei tells the class of his past as the original God of Death and how meeting Aguri would influence him into becoming a teacher. He also revealed that the antimatter inside of his body will eventually blow up, kill him and destroy the world by March if no one is able to assassinate him. Now knowing the truth, the class spent the winter break with very little activity towards planning his assassination. Two days before term begins again, Nagisa was among those who visited Kayano in hospital. He apologised to kissing her on a whim to save herself which Kayano seemingly brushes off.

Schism Time: A Divided Class
Still reeling from listening about Korosensei's past, the class returned to school with very little enthusiasm and with two months before the March deadline. Having thought about it during the winter break, Nagisa calls the class for a meeting after the day's end. In the mountains he voices out how the class feels and proposes that instead of killing their teacher, they find a way of saving him. Most of the students seem to agree with Nagisa,  Kurahashi and Kataoka being among the first to express their support. However Nakamura and Terasaka's group disagree to Nagisa's surprise. Nakamura states that the bond that was continually developing between assassin and target is precisely why Korosensei has to be killed while Terasaka's group observes the slim chance of coming up with a solution within two months, time which could be productively used in planning for more assassinations.

Karma is the most vocal opponent; he accuses Nagisa of becoming too confident as his talent for assassination grows, and walking over others who work hard to kill their target despite not having any talent. Nagisa retorts that given everything Korosensei has done for the class, it feels right to try to save him. The argument quickly becomes violent when Karma crosses the line by insulting Nagisa's appearance and goading him to fight, escalating into a scuffle between the two close friends. Each was pulled away from each other by Maehara, Isogai and Sugino until Korosensei himself arrives to mediate the situation. Not wanting a schism to divide the class after nearly a year of standing united, Korosensei establishes a team death match, capture the flag paintball game, where the winning team's opinion will dictate the class's next step. Nagisa watches on as the class divides itself up and, seeing more of the students joining the red (kill) team than he initially thought, begins doubting about being so sure of his opinion. After joining the blue (save) team, Isogai allows Nagisa the freedom to do as he sees fit before the match commences, nothing that as Nagisa lacks battle strengths, it is more advisable to let him do what he thinks best than to command him.

For most of the battle Nagisa is nowhere to be seen. When both sides are down to the last few, Nagisa comes out of hiding and ambushes Nakamura, Terasaka, Muramatsu and Yoshida as they head for the blue team's flag, completely obliterating Red team's attack strategy. Many are impressed that Nagisa had hidden behind Karasuma who was in the perfect position to referee the battle until the moment presented itself for the boy to eliminate as many as possible. With both teams down to their last man, Karma calls out to challenge Nagisa to a one-on-one duel. Not wanting to divide the class any further, Nagisa comes out and drops his gun despite having a clear shot and Karma's close combat advantage. After reminiscing their past friendship, the two resume their earlier fight but Karma continually has the upper hand despite being disarmed and allowing Nagisa to hit him.

Karma eventually strikes Nagisa with an uppercut followed by an axe kick, seemingly knocking Nagisa unconscious. This proved to be a ruse as Nagisa uses the clap stun technique when Karma prepares to end the fight, though the shock is somewhat negated due to the opponent biting his tongue. Nagisa nevertheless rises and brings out his holstered knife, and appears to allow his bloodlust to rage. However he catches Karma off guard by throwing the knife filled with his bloodlust at him, causing Karma to deflect it and get caught into an arm chokehold, intending to make Karma lose unconsciousness. In a vain attempt to throw Nagisa off, Karma finds his discarded knife but chooses not to strike him. Instead he surrenders and Nagisa wins the war for the blue team. The two friends reconcile with each other, dropping the honorifics in the process. Karasuma decides the honour the agreement but on the condition that come February the class resume their original goal to kill Korosensei should they fail to find a way to save him.

Outer Space and Final Resolve
The class comes across information about US research of the antimatter within Korosensei. However the experiments are being conducted at the International Space Station, with supplies launched from a Japanese launch site. The class infiltrate the site and selected Nagisa and Karma to hijack the ISS with Ritsu's help. The two boys replaced the crash test dummies with themselves and, after launching to the ISS, took one of the inhabitants hostage with a rubber knife and fake bomb. Fortunately for Nagisa and Karma, the astronauts (some being soldiers) agreed to hand the data over to them provided that they helped unload the supplies. The pair soon returned to Earth with Ritsu and Korosensei's help and landed safely in Class E's pool.

With Okuda's deciphering of the data, the class learned that there is a solution to save Korosensei based on the poison she concocted in the first semester. Futhermore, the chances of Korosensei self-destructing is less than 1% due to his large size compared to the test mouse that caused the moon to explode. Despite having a solution at hand to save their teacher, Karasuma points out that the government will not retract their mission and Korosensei is still dangerous. Nagisa resolves that they resume their assassination attempts on Korosensei until their graduation. At that point they can leave the outcome to the world governments should Korosensei still be alive by March.

Entrance Exams - Time to Decide
As the entrance exams approach, Nagisa has already decided on the high school and university he wants to enter according to his mother's wishes. However he is worried about what he wants to become afterwards, compared to the rest of his classmates who had already decided on their future careers. It is during his tutelage of Sakura at the Wakaba Park nursery that the girl planted the idea of Nagisa becoming a teacher. While the boy knows he can never be like Korosensei, he does admire him and realizes that those who admire others for saving their lives (doctors) or having a particular skill (such as hit men) could eventually become whom they admire. After the exam, Nagisa's score placed him on the waiting list. Korosensei however comforts him that as others would take different entrance exams, Nagisa essentially passed.

On Valentines' Day, Nagisa attempted to mediate the situation between Okano and Maehara but was knocked out by the former throwing a chair to his face. Later he was pulled aside by Kayano who asked him whether he had decided on a career. Nagisa only gave a vague answer but sees Korosensei perched on a tree. He considered striking but then relented as he was too far away. At that moment Kayano gave him her box of chocolates, stunning Nagisa to stutter that he should be thanking her instead of the other way around.

Later in the month, Nagisa had been accepted into his first high school preference. Korosensei celebrated the occasion by collating a graduation photo album with the class, though the students ripped up most of the 'private photos' their target had secretly taken. After calming Sakura down as she remembered her bullying experiences during another tutoring session, Nagisa later met with Korosensei for the careers consultation, and finally confirmed that he wanted to become a teacher.

Assassination Time, 2nd Period
That night, (one week before the deadline) Korosensei was fired upon by a satellite weapon called Lance of the Heavens and immediately trapped in the classroom by an unbreakable dome shield dubbed Earth's Shield. Nagisa and the rest of the class rushed to the school but were blocked by army soldiers guarding the perimeter at the base of the mountain and forced to escape the hounding media. After briefly scouting the perimeter the whole class was quickly snatched by elite mercenaries (the same men that a few of the students briefly confronted earlier) and brought before the bureaucrat in charge of the operation, the official reason being that the students' safety after being presented as being held hostage by Korosensei for the past year.

The students were soon confined inside the makeshift command centre and listened helplessly to the media vilifying Korosensei and presenting Class 3-E as having Stockholm Syndrome. Karasuma later met the students and stated that there was nothing he could do to free them when the class should have waited. The security perimeter was well guarded until the fifth day when the soldiers become more lax but the area between the perimeter and the school would be guarded by the mercenary group led by the legendary soldier Craig Houjou named Wolfpack. Nagisa pleaded with Karasuma to let them go to Korosensei but Karasuma threw him down, told the boy to not cause trouble for him, and left the class to cool their heads for the next three days. Nagisa immediately realised what Karasuma actually meant, referring to a conversation the two of them had a few days ago, and relayed the information their teacher had just told them.

Knowing that the class did not have the heart to truly kill Korosensei, they could not allow a group of strangers finish the work in a few hours that the students spent a whole year for. The class spent the next three days biding their time, planning their infiltration and defeating the enemies stealthly. On the fifth and final day, Irina briefly greeted the class and kissed Nagisa and a few other students. After she left those kissed spat out components of Takebayahsi's explosives and used it to escape their makeshift jail. Nagisa headed back home to prepare but was confronted by his mother Hiromi. Although scared at the sight of her, Hiromi allowed Nagisa to go ahead, the boy happy at finally being understood. With only three hours to go before the deadline, He and the rest of the class race to the mountain classroom. Under Karma's direction the students efficiently subdued the Wolfpack mercenaries who had severely underestimated their abilities thanks to Karasuma's false intel. Houjou however put up more resistance but the class adopted a hit and run strategy they had settled on during their confinement. Eventually a tranquilliser dart struck the mercenary, allowing Nagisa to successfully use the stun clap technique to daze him and Karma followed up with a swift axe kick to defeat Houjou. With 90 minutes left on the clock, the class penetrated the barrier and happily reunited with Korosensei.

Their celebrations however were brutally interrupted by the arrival of Shiro and Korosensei's former apprentice (No. 2) who was now a hideous tentacle monster. All three proceeded to fight, where it was obvious to Nagisa and the whole class that not only was Korosensei being overwhelmed but the ferocity of the fight was nowhere near the amount of time the students trained themselves to be assassins and were completely helpless to intervene. They also knew that Korosensei could not reach his full potential while the class was present; hence they were his critical weakness. Shiro then orders No.2 to attack the students, forcing Korosensei to take the full brunt of the attack to protect them. The repeated attacks prompt Kayano to intervene and distract No. 2. However to the horror of Nagisa and everyone else, their classmate was pierced through the chest. Korosensei turns black as a result and proceeds to violently attack the God of Death, prompting Nagisa to grab the unconscious Kayano and move away from the fight.

The Chosen - Time Has Come
Korosensei eventually defeats Shiro and his former apprentice. Nagisa prepares to set Kayano down but Korosensei prevents him to avoid any more bacterial harm. Using the blood collected, he brings Kayano back to life to the joy of Nagisa and the class, though he soon collapses from exhaustion. With less than half an hour away until Lance of the Heavens fires its antimatter cannon, Korosensei addresses Class 3-E that the assassins should not miss their dying target and that the inevitable has come. He further states that all good times must come to an end, hence the classroom. The students, after briefly discussing whether or not to kill Korosensei with their own hands, ultimately all decides to continue maintaining their 'bonds' as assassins and a target by lending their hands on giving him the final peace. Utilizing the weakness #37 (grabbing all his tentacles at once makes him unable to move), the students grabbed all of Korosensei's tentacles, sealing his maneuverability. Nagisa volunteers to perform perhaps the harshest task: deliver the coup de grace to their teacher's heart with an anti-Korosensei knife which no one can complain about it that Nagisa will be the one to execute Koro-sensei.

After Korosensei completing the final attendance and bidding farewells to students and faculties, the time has come for Nagisa to deliver the final thrust. But the feeling of uncertainty causes Nagisa to 'kill through killing emotion'. Korosensei then calmed him his brainwave, telling him to kill with 'calm and smile'. Nagisa, having regained his composure, bidded his teacher a tearful goodbye and plunged his anti-Korosensei knife into the heart of the teacher. Korosensei then turns into many shining particles of light before disappearing for eternity, leaving only his clothes and cap. Nagisa and whole class 3-E then wailed in profound grief.

They head inside the classroom and fall asleep whilst reading the graduation album and book of advice Korosensei had written for each of them. Nagisa attends the school's graduation ceremony along with the class at the town hall, with Chairman Asano parting ways on good terms. To the boy's surprise, he finds his mother and father watching their son's graduation together. His father reveals that Korosensei had approached him one month before to state Nagisa's wish for his parents to be together once more. Happy to hear that they are willing to start over, Nagisa leaves with his class, escorted by Gakushu and his friends to protect him and Class 3-E from the media that are attempting to interview any of Class 3-E members about their beloved teacher..

Aftermath - Killing Time
After graduation, Nagisa began to enter the high school his mother wanted him to study at. He graduated and then began studying as a teacher. Seven years after Korosensei's assassination he became a student-teacher at Paradise High School as the Homeroom Teacher of Class 3-5, a class that was messed up and full with male delinquents. He was bullied at first for his short stature and androgynous appearance and the leader of Class 3-5 threatened to kill him if Nagisa continued to order his class around. At the word "kill" Nagisa used the Clap Stun technique and quickly manuveurs behind him, pointing his middle finger on his neck and surprising all of the class. Instead of punishing him however, Nagisa encouraged him and bids him good luck to try and kill him until he can graduate. As Nagisa walks towards the front, the leader of the class sees the overlapping shadow of Korosensei on Nagisa. Looking at his students, Nagisa smiles as he took his attendance book again and start the class.

Nagisa is seen having a field trip with his class 3-5 students at the end of Extra Story 4: even though he seems to have some modest success in taming the delinquents, he is still far from earning their full respect as they are annoyed at his clumsiness.

Kaede Kayano
Kaede is another one of Nagisa's closest friends and the two sit next to each other in class. Out of all the females, Kaede is definitely the one he's closest to. They get along well and are often seen together and were paired together during the Assassination Test of Courage. It was revealed in Chapter 130 that Kayano is the reason for his signature pigtails and that she was using him to mask herself. When Korosensei later attempts to remove Kayano's black tentacles, Nagisa uses Irina's special kissing technique on Kayano to distract her from her bloodlust so Korosensei could remove the tentacles from her neck. The two are still close friends after Kayano's near-fatal assassination, though Nagisa is currently unaware of Kayano's strong romantic feelings for him; which, according to Rio Nakamura stems from his low self-esteem.

Karma Akabane
Karma is one of Nagisa's closest friends and the only person Karma will seemingly listen to. They were in the class for their first two years of middle school which continued into their third year. Unlike many people, Nagisa is unfazed by Karma's violent behavior and although they have basically opposite personalities, they do have similar interests and get along well. Karma also enjoys teasing Nagisa, but the latter doesn't pay it much mind despite often being incredulous to the extent of the teasing. According to the official character book, Nagisa is the only person to have visited Karma's house.

It has been noted that Nagisa greatly admires Karma's brilliance and easygoing personality. Chapter 147 reveals that this has been the case since their first year, and was happy when Karma asks him out to see a movie together which in this case, is Sonic Ninja. They hung around a lot but their friendship was short lived. Nagisa believes that Karma simply became tired of 'sharing the stage' with him, particularly when Karma became violent, and invitations gradually became rare. Karma sees Nagisa as an honest, nice and harmless person who he can be less guarded with. But after being surprised by Nagisa in a fast food outlet with what felt as though Karma had been stabbed in the back, he did not know how to respond to the mysterious feeling hiding within his friend, which led to the two drifting apart. By the time of Karma's suspension their relationship went back to being just classmates, until reuniting again in Class 3-E.

Tomohito Sugino
Nagisa and Sugino seems to be good friends since Chapter 2 and have been closest friends in Class E and are often seen hanging out together.

Rio Nakamura
Nagisa sits beside Rio in class and the latter often teases him and plays on his androgynous appearance which is listed as one of her hobbies. Despite that, the two get along well and Nagisa doesn't pay much mind to her teasing. Unaware by him, Nakamura has a crush on him which ended up surrendered after she let Kayano make her move to gain Nagisa's affection.

Korosensei
Main article: Korosensei

Korosensei is the first teacher Nagisa feels sees him head on, as Nagisa himself has had bad experiences with the teacher from his school since they only cared about grades and once he dropped they treated him like garbage. While he frequently tries to kill Korosensei, he also respects and cares for him as a teacher and a mentor, and arguably even a parental figure. Korosensei, in turn, particularly focuses on Nagisa's development and watches out for him, especially since he can sense Nagisa's hidden bloodlust and low self esteem. He is arguably Korosensei's favorite student and Korosensei even helped him stand up to his mother and demand freedom. He even helped his mother and father reunite together for Nagisa's sake as a family. When there was a chance Korosensei could be saved, Nagisa was the first who suggested they should. However, he ultimately was the one who killed Korosensei, crying the most when he had to. As he grew up, Nagisa followed his former mentor's example and became a teacher (ironically with a bunch of delinquents) and used the assassination skills he learned to keep them in line.

Tadaomi Karasuma
Karasuma thought that Nagisa was a mild student with no special physical abilities. However, he did sense the presence of Nagisa's natural talent for assassination. Because of that, he chose Nagisa to challenge Takaoka in a "mock assassination", which Nagisa skillfully won. Like most of Class E's students, Nagisa is fond of him, due to the fact that Karasuma treats him and the others as a professional equal. Nagisa learn several techniques from Karasuma such as Triangle arm choke that he use later on Civil War arc against Karma.

Irina Jelavić
Though initially it began with Irina's ruse to get information on Korosensei with a 'Kiss of Death "30 hits"' and timidity on the part of Nagisa, the two eventually become good allies with the good bonds of teacher and student. On several occasions, Irina demonstrated some valuable techniques as an assassin to Nagisa. Likewise Irina is surprised by Nagisa's hidden talents and bloodlust, the more notable examples being outsmarting a combat veteran such as Takaoka in a fight and subduing Kaede Kayano with her own technique: the Kiss of Death.

Lovro
Instructor during Summer Break, Lovro heard about his traits of defeating Takaoka from Karasuma which gain his interest about his assassination skills. He saw Nagisa as a pure talented assassin by just looking at him and he is the only one that was willing to teach Nagisa his Clap Stun technique which later Nagisa used it for the first time to defeat takaoka for the second time. Aside of Hayami and Chiba whom he values as a great marksman, Nagisa in the other hand was valued as a pure talent assassin.

Yūji Norita
Yūji is a rich boy Nagisa met in Chapter 66 when he was forced to crossdress during a mission to save the remaining students of Class E. Yūji fell in love with Nagisa after seeing his smile and the latter teaching him what it means to be cool. They meet again in Chapter 117 where Yūji revealed that he had been searching for Nagisa ever since their first meeting. Nagisa then reveals to Yūji that he is male and teaches him that he can turn his weaknesses into strength and though shocked (and heartbroken), he still considered him a friend.

Sakura
Sakura is a young girl Nagisa sometimes teaches at Wakaba Park's Nursery. He had problems connecting with her at first, but eventually he was able to befriend her and help her with both her studies and her bullying problems. Sakura is also very fond of Nagisa due to his kind nature. Afterwards, he became her personal tutor. Sakura was the one who gave Nagisa the idea of becoming a teacher which he later decides to follow.

Abilities
Assassination: Nagisa's physical abilities are mediocre, and it worthy to note that he is one of the weakest amongst the boys. If a comparison were to be made, Nagisa's constitution and strength are more easily comparable to a female of his age. However, Nagisa has an extraordinary amount of natural talent as an assassin as shown in his duels against Takaoka. This inclination has also been made apparent numerous times during the span of the story. He is described by Korosensei to be a  'pure assassin'. Several other characters such as Karma and Maehara have noted that he is full of surprises - one can never know when or where Nagisa will aim to strike. His talent in the art of assassination has garnered respect from even those who are not his peers, and there are times when others have commented on the potential Nagisa possessed that could be fulfilled in the role of a professional hitman. In the end, though, Nagisa does not pursue this path and decides to use his abilities to help others in the same way Korosensei did.

Bloodlust:Nagisa possesses a frighteningly massive amount of hidden bloodlust despite his initial character, impression and appearance which can affect his opponents in varying ways; the most significant, powerful reaction involve immobilization and an inability to counterattack or to fight back, and this type of reaction affects even trained, jaded assassins. This is made very clearly evident for the first time during his mock assassination with Takaoka, and another early event is the incident when two of Nagisa's old classmates threatened him. This unique talent has sparked the interest of all three of Class E's main faculty. When Nagisa's bloodlust is released or directed at someone, it is metaphorically represented as a large, blood-soaked snake coiled around Nagisa's target with its fangs bared and ready to strike at any moment. In later chapters, his bloodlust takes the form of a flaming aura around him in a way that either mimics or reflects that of the God of Death. However, if Nagisa were to lose control of his bloodlust due to emotional provocation, his inability to rein his bloodlust back under control is indicated in his eyes, which are illustrated as dull. Nagisa can grow reckless or lack foresight during combat while focusing on his target, and opponents with bloodlust that exceeds Nagisa's own are not affected in the slightest.

People Reading/Discernment: Nagisa developed the ability to read people's expressions and intentions with ease as a result of his past experience with his mother, Hiromi Shiota. There are occasions when he can detect if a person is lying or not being entirely truthful (e.g. Terasaka when he is plotting with Shiro). After being placed on the receivingend of the God of Death's improved Clap Stunner, this ability somehow later evolves into a sort of advanced ability that allows Nagisa to analyze a person's state of mind simply by looking at them. This is illustrated and/or described as "wavelengths" or "wavelengths of consciousness" of people that represents their breathing, line of sight, facial expression, body language and more. This ability allows Nagisa to find a person's "gap in consciousness" or, in other words, openings where they let their guard down as well as their "peak in consciousness", which is the state of mind i which a person is highly susceptible to outside stimuli such as the Clap Stunner, which he has made effective use of in different ways, from stunning enemies before attacking them to simple, almost trivial things such as being able to remove a size label from clothing without the person wearing it noticing.

Marksmanship: In June, Nagisa scored 84/200 in Marksmanship, making him the fifth best among the boys and seventh overall amongst his class.

Kiss of Death: Nagisa has shown some level of skill when using Irina's "Kiss of Death" technique, able to acquire 15 "Hits" off of Kaede. Supposedly, unlike the others in his class, Nagisa is quite excellent with a lot of potential for improvement in this particular skill. Irina has remarked that Nagisa's training in indiscriminate French kisses have bestowed on him remarkable enough skill to exceed his classmates by a large margin. Such margins are represented numerically, as Nagisa is supposedly capable of registering a total of 40 "Hits" if he were to place more effort into his kiss.

Quotes

 * (About Korosensei) "I might just be able to kill him. After all, this teacher can't see me, either."
 * (About Korosensei) "Chew out at Mach 20, then praised with waving tentacles... This unusual education made me pretty happy. All because this unusual teacher was actually looking at us head-on."
 * (About Korosensei) "We've never assassinated anyone before, and there's plenty of other stuff we should be doing. But you know... I think this teacher might even accept my bloodlust."
 * (To Korosensei) "Before you destroy Earth... I'll kill you."
 * (To Akira Takaoka) "I feel that Karasuma-sensei, who devotes himself to being professional, is much kinder than Takaoka-sensei, who forcefully passes off as a father."
 * (To his former Class D classmates) "Kill me, huh? And yet it looks like you've never killed someone before."
 * (To Kaede Kayano) "I want to know more about everyone, try killing sensei more, and live so I don't leave anything unfinished."
 * (About Kaede Kayano) "I won't let you say it, Kayano. I won't let you say it was all an act! All of our Class E memories... All the good times we had... You could never block them out entirely. I won't let you say that you were only focused on your revenge."
 * (Final words to Koro-sensei moments before execution) "Goodbye... Koro-sensei"
 * (To Class 3-5 Students and final words)"Please be seated. I will now begin Class"

Trivia

 * His favorite food is sushi according to Chapter 2, he is later seen eating it with his father.
 * His favorite subject is English while his least favorite subject is Science.
 * His hobby is researching.
 * His past club before dropping to Class E was Concert Club.
 * He was called "Gender" during the class 3-E training using code names. Nakamura was the one who gave him his codename.
 * Nagisa is the shortest male student of Class 3-E.
 * If he earned the reward from killing Korosensei, he'd like to buy himself some height.
 * Nagisa appears as a Story Mode NPC in the PS3 game J-Stars Victory Vs, along with Irina and Karasuma.
 * In the art rankings of Volume 5, Nagisa placed 5th among the male students.
 * Nagisa is one of the few people in the entire manga who is referred to by his first name (similar to Karma), when nearly everyone else are referred by their family name. According to Koro-sensei in his talk with Nagisa's father, it is because Nagisa asked everyone to call him by his given name so he could easily make the transition back to his old name if his parents ever ended up getting back together.
 * He is usually represented by a snake due to his ability to hide his bloodlust and strike at the least expected moment. In Chapter 147, this is taken a step further where instead of simply being represented by a snake, he is represented, in Karma's perspective, by a version of himself that resembles a Gorgon due to snakes being heavily involved in their appearance.
 * In the popularity poll of Volume 12, he was ranked 2nd.
 * He is the only student that takes note of every weakness of Korosensei, however insignificant.
 * By the end of the Class 3-E Civil War, Nagisa is the last man standing with a score of five kills (including Karma's surrender), the highest of the class followed by Rinka Hayami (four) and Yukiko Kanzaki (three). He is also noted as the fastest kill streak in just a second (four kills in one second) and shares the kill streak with Hayami in terms of kill with four kill streak (Exclude Karma who surrenders).
 * In the Assassination Classroom spin-off, Nagisa's bug is that when he takes a step forward with a strong will, it will have a random effect.
 * In the Assassination Classroom extras, a girl named Hotaru that was working in a restaurant with her parents appears to resemble Nagisa, only with slight different such as hair.
 * It is highly possible that due to high request that the fans want to see Nagisa in female version, the author decide to create Hotaru as a main character on the Assassination Classroom extras.
 * For Nagisa himself, a word "Kill" directly when being threatened was much like a magic word for him that enable him to use his assassination abilities.
 * In the tankobon extras, his statistics were listed as:
 * Physical strength: 2
 * Mobility: 3.5
 * Close-range assassination: 3.5
 * Long-range assassination: 3.5
 * Academic ability: 3.5
 * Characteristic skill: 5 (anti-human assassination)
 * Nagisa was the one to complete the assassination by stabbing Korosensei in the heart with an anti-sensei knife after he volunteers to be the one to end Korosensei's life.
 * In episode 24,there are various messages left on a blackboard by Korosensei and 3-E students.Nagisa's message was "It's great to meet you guys!"