Pre-augmentation of the Antimatter tentacles This is further reinforced by his lack of a face, which he cut out to better facilitate his face-changing disguises.
The Reaper, also known as the God of Death, is the original human identity of Korosensei, the supporting protagonist of the Assassination Classroom series. He was the world's greatest assassin until his student betrayed him and stole his identity.
Devastated by Aguri's death, The Reaper wished to be weak and flawed, and his tentacles transformed him into the kindhearted teacher Koro-sensei.
The God of Death, also known as The Reaper, is a major and the final antagonist in the Assassination Classroom series. He was a protégé of Korosensei. The title “God of Death” initially belonged to Koro-Sensei, however upon betraying him he stole his identity and name.
Antimatter Physiology: Due to the human experiments of producing antimatter in a living body by Shiro, Korosensei's entire appearance is that of an octopus-like creature with multiple tendrils that function as his tentacles.
After being used in experiments, Korosensei acquired the appearance of a yellow bipedal octopus. He is about three meters tall and possesses a large, bulbous head with a large smile and small, beady eyes. He uses two feelers as arms, with two fingers each, and utilizes the rest of his tentacles to walk with.
The series is narrated by Nagisa Shiota, one of the students in the class whose main strategy in killing Koro-sensei is making a list of all his weaknesses over time. At first, Nagisa appears to be one of the weaker members of Class 3-E, but he later emerges as one of the most skillful assassins in the class.
Kotarō Yanagisawa, better known as Shiro, is the main antagonist of the manga and anime series Assassination Classroom. He is a cruel and vengeful scientist who bears a deep grudge against Koro-Sensei because he was the one who stole everything from him.
Koro-sensei (殺せんせー, Koro-sensē) is the main protagonist and anti-hero of the series.
Aguri Yukimura is the deceased love interest of Koro-sensei in the anime and manga series Assassination Classroom. Aguri was the teacher of Class 3-E and the older sister of Akari Yukimura, better known as Kaede Kayano.
The government had both experienced scientists and the money required for that. Even with the cure, there was a 1% chance that he might explode. No government in the world would have taken such a risk even if the chances of an explosion were as low as 0.001%.
The students plan the killing during the summer holiday, where they reminisce about their kind past teacher, Aguri Yukimura. Eventually, Class 3-E manages to bind Koro-Sensei thanks to Nagisa's observation of his weakness: water. However, Koro-sensei transforms into a ball to avoid being killed.
Koro-sensei's last words to him are those of pride and regret that he hadn't been more attentive, and promising that if they meet again, he'll treat him better.
1 Nagisa Shota
Though a bit timid at the start of the series, Nagisa quickly rose to prominence as Class 3-E's best assassin, mastering the powerful Stun Clap technique when none of his classmates could.
Karma is unquestionably the ace of the class. From his introduction, he's shown to be on a different level than everyone else, displayed to be a better fighter and stronger than everyone in the class. He's the third best marksman in the class, and the smartest of them all.
Marksmanship: Chiba is the best marksman among the boys (and all of Class 3-E). He excels in spatial calculation and, as such, is unmatched in long distance shooting.
Goku's access to Instant Transmission means that no matter how fast Koro-sensei moves, Goku can keep up and eventually win.
However, Koro-sensei was still bored with his new position, with no one worthy enough to challenge him. That led him to become a teacher in order to train students to be warriors strong enough to defeat him. The students of Class 3-E storm through the castle to get to the Demon King.
While it's not clear exactly how well Koro-sensei can stand up to energy-based attacks, he does have access to some Ki abilities that might make him more able to counter a Kamehameha than one might expect. In the end, Goku seems most likely to win, if only because of Koro-sensei's eagerness to coach his opponents.
For Karma, he saw Nagisa as a harmless person whom he can let his guard down.
Weaknesses: Makes mistakes if he is overconfident (In preparation for the end of semester exams, Karma adopted a lazy approach, believing he would ace the exams with no problem. As such he ignored Korosensei's concerns and did not join his classmates in study sessions.
Before dying, Korosensei conducts a final roll call, with Karma first to respond. After Nagisa finally kills him and Korosensei disappears in particles of light, everyone starts crying including Karma.
The government saw him as a secret that had to be silenced and nothing else. The ending itself presents the death of Koro-Sensei by the hand of his students, after they lost all their will to assassinate him. They put his life to an end the way he wanted, but they lost the best teacher they ever had.
Korosensei is a good character and I'm sad about his death, however he is serene in accepting his death, since now his students can face the world without him and he doesn't worry about anything anymore, hence Koronosensei's peace of mind for me it's contagious and I also see it in the poetic since ...