Disclaimer: Significant story spoilers for Assassination Classroom ahead! Proceed with caution.

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One of the most pivotal moments in the entire show was when Koro-Sensei revealed his backstory to the E class. Koro-Sensei’s motivation for becoming a teacher, the reasoning for his expertise in just about everything and the history of his tentacles were all revealed. It was a touching backstory that changed the dynamic of the episodes to come.

It was also revealed that Koro-Sensei was effectively a ticking time bomb, set to blow up the earth regardless of whether or not he is killed by the class.

And thus, Nagisa raises a proposal. A proposal that may sound preposterous to some, but reasonable to many. Nagisa wants to save Koro-Sensei instead of kill him, and he wants to dedicate the class’ remaining time into finding a way to prevent the explosion instead of killing him further.

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Such a proposal literally tore the class in half, with both sides having their own reasons as to why Koro-Sensei deserved to live or die. And regardless of the side we as the viewer chose, it must be acknowledged that both sides of the argument have very valid reasons. There is no right or wrong answer, just people with different ideas about life.

So, let’s take another dip into the world of philosophy and see whether you fall in Team Nagisa’s ‘don’t-kill’ or Team Karma’s ‘Kill’.

Team ‘don’t kill’

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Before I start on this viewpoint, it’s worth pointing out that the show gives a lot of bias to this side of the team. The event was indeed a plot point to bring the class into a new direction, but more than that, it was a transformation point for Nagisa’s character as he stands up to Karma. As such, this side is subtly portrayed to be ‘the correct side’ and the side that wins out in the end, although both sides have valid viewpoints.

Koro-Sensei, despite having the having the fundamental bond of ‘assassin and target’, had been nothing but kind to the class. In fact, it’s hard to deny that the class as a whole came as far as they did because of Koro-sensei’s guidance and help. Without Koro-sensei, Nagisa, Karma, and everyone else would still be stuck in the hopeless pit they were in at the beginning of the series, with no desire to escape or better themselves.

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So, why on earth would the class want to kill Koro-Sensei rather than save him? He is clearly capable of incredible feats of genius, and his survival would surely benefit the world.

The reason why the assassin and target bond was created in the first place was due to the idea that Koro-sensei was painted as a super-malicious being bent on destroying the world in March – which we now know to be untrue. So, why should everyone be pulling their efforts to put an end to a super monster when that monster isn’t even destroying the world with any malicious intent?

Being basically a ticking time bomb, Koro-Sensei isn’t a villain – he’s a victim.

Koro-Sensei deserves compassion and care and not bloodthirsty stares. After all, if the rule ‘treat yourself the way you want to be treated’ falls true, why does Koro-Sensei deserve death?

screencap 8It’s difficult to justify killing someone who has done nothing but support the class, even if their fundamental bond is that of an assassin and target. At this point, the ‘save’ side of the class values their bond with Koro-Sensei far more than 10 billion yen, and it’s not difficult to see why this is the case.

The students aren’t exactly moral saints – they’ve been acting with the intent to kill up until this moment. However, the fact that they haven’t done harm to anything that hadn’t threatened their lives up until now shows that they are something that the government likes to forget: they are thinking, feeling sentient creatures with moral codes. Should they be logic driven, cold-blooded killers, they would have likely concluded that 10 billion yen is a prize too insane to give up.

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But by being true to their own feelings and following what they feel to be righteous, they’re willing to surrender the cash prize if it meant saving their teacher. In their hearts, saving Koro-Sensei is their ‘right’ way, and being true to their feelings involves seeing their ideals till the end, even if it puts them into conflict with other class members.

Team ‘kill’

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It at first sounds pretty preposterous as to why killing the teacher who has done nothing but nurture and support the class is a good idea, but there are indeed justifiable reasons.

A driving reason that compels Karma and his crew is the idea of duty and responsibility. It was made clear to them at the very start – before they are student and teacher, they are assassin and target. One set of roles precedes the other, and Nagisa’s proposal to find a way to let Koro-Sensei live is evident that he has confused the order of these roles.

Keep in mind that this isn’t about the money anymore – that was barely brought up in the debate. Of course, choosing to ‘save’ Koro-Sensei effectively surrenders the money, but that’s not a driving force. What’s more important is the idea that assassination holds the classroom together.

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Assassination is what brought the classroom together, and it should be what seals the graduation ceremony. Abandoning the philosophy that brought the classroom so close together in the first place would be an insult to all the effort that was poured in earlier.

The fact that it’s Nagisa in particular who brings up the idea of saving Koro-Sensei doesn’t really help the case either. Nagisa is, without a doubt, the most competent assassin in the class, and for him to surrender the talent that he was gifted with for a different solution undermines the effort that the other less talented students have put in trying to catch up with Nagisa.

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Karma puts this best when he calls out Nagisa. He makes it clear that being the one with the most innate assassination skills, ones that easily surpass the rest of the class, he should be the one leading the charge to kill the octopus teacher, not the first one to back down.

If the most talented assassin in the class declares that killing their target is the wrong thing to do, what are the people who have poured in hours of effort to catch up to do? It’d be insulting the talentless students working super hard to master their craft. Karma’s analogy, while a bit absurd, is completely correct in this context:

“It’s like a hot woman telling a bunch of homely ones that they should stop trying so hard to find boyfriends.”

Nagisa, while having good intent, is being selfish with his demands as rightfully picked up by Karma. To leave something half-done in favour of something that may or may not lead to a dead end is pretty reckless. Not only that, Nagisa being the most gifted killer of the entire class is unable to sympathize with those who have worked super hard to catch up to a standard even remotely close to his. That explains why he was so willing to surrender what he got through talent, whereas others are unwilling to do the same because they worked hard for it.

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One of the reasons why Koro-sensei should be focused on being killed and not saved that is not brought up in the show is the idea of an “Existential Risk Calculus”.

An Existential Risk Calculus is a philosophical stance that states that if the consequence of an event is global annihilation and human extinction, even a small possibility of its occurrence is unacceptable. Even if there is a 99% chance of nothing but good, a 1% chance is still too high if the outcome is the end of the world. The smallest possibility of an apocalypse is unacceptable and it should be discarded entirely. This is usually applied to Nuclear warfare, as such weapons are generally sensitive to terrifying consequences should they be misused.

In this example, even after the success of the ‘don’t kill’ team and a remedy is found, the possibility of Koro-sensei’s explosion got knocked all the way down to less than 1%. This does, at face value, sound great. There is a 99% chance that Koro-Sensei can live on, continue to guide the students and generally do good.

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However, that 1% chance still exists, and to someone following the Existential Risk Calculus, that 1% is still too high. This is because that should the world be cruel and unlucky, and the 1 in 100 does happen one day, that’s it. The end. The city, the ocean, humanity as a whole would all cease to exist. How can such a consequence be accepted?

It doesn’t matter how amazing the other 99% is. Koro-sensei could continue working as a teacher, or become an ambassador, or create world peace, and it still wouldn’t be enough. The fact of the matter is, there is a <1% chance that Koro-Sensei can end the world, and as long as that tiniest chance still exists, Koro-sensei cannot be allowed to live.

Does this sound familiar? It might if you’ve watched Batman vs Superman.

Why does Batman oppose Superman’s existence? Because if Superman were to one day choose to go against humanity and the world, nobody would be able to stop him. He’d be able to wipe continents off the face of the earth if nobody prepares for such an outcome. That’s why Batman chooses to take to kill Superman for a large part of the movie – it doesn’t matter how good or right or helpful Superman is. If a being with that much power has even a small chance to turn their back on the world, it needs to be put to rest.

So, what happened?

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Through an incredible fight scene, Nagisa’s team defeats Karma’s team, and the class accepts his ideology. The class then works together in search of a cure for Koro-Sensei, and they later discover that Koro-Sensei already cured himself with a solution that he created very early on in the story. It seems like a happy ending is in sight – it doesn’t seem like there’s a need to kill Koro-Sensei at all.

However, the world’s governments aren’t satisfied. Clearly having ideologies that more closely mirror Karma’s side of ‘kill’, they have put a plan into action so effective that even Koro-Sensei is forced to submit. A combination of the world’s greatest efforts resulted in the yellow octopus being forced to lay his life down the line.

But here, we see where Koro-Sensei himself stands on the matter.

Koro-Sensei, despite talking about his own life, admits that it should be better if he were killed off.

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He knows that he’s someone who can bring great good to the universe should he choose to do so. His intellect, physical capabilities and experiences in both assassination and academic teaching can allow him to change the world into a much better place.

However, what can’t be denied is that Koro-Sensei is essentially an uncategorized super-being with incredible destructive potential. The world isn’t just going to let this slide. Putting an end to Koro-sensei’s life may be what is best after all, not because Koro-sensei did any wrong, but instead because Koro-Sensei doesn’t belong in this world.

To quote Koro-sensei himself:

“Even if I don’t explode, you can’t expect all these nations not to be afraid of a creature like me. Sooner or later, they’ll want to snuff me out. It’s only reasonable.”

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No longer a state secret, Koro-Sensei’s survival will surely spell discord for the world. Even if he doesn’t explode, the idea of someone so much more powerful than human comprehension just wandering around is surely going to raise some controversy.

It’s also important to take a second to appreciate the beauty of the scenario the finale presents us with. Everything pointed to the inevitable fact that Koro-Sensei had to die, but never in a manner like this. All doors are closed. The idea of the students acting as Koro-Sensei’s hostages was even brought up to somehow cease the laser, but if the government is consistent with their philosophical standing, the death of a few students is a small price to pay for making the octopus disappear.

The assassination was more than just an obligation given to the students by the government. At this point in the story, the assassination itself became symbolic of the student’s development in the story, and especially in these last moments, symbolic of their graduation.

The only way for the students to get out of the scenario was to do what they had to do: Kill Koro-Sensei and graduate from the Assassination Classroom.


Assassination is Koro-Sensei’s mandatory course. The class of 3-E are his students, but they are also his assassins. A day does not pass where Koro-Sensei is not conscious of this fact.

screencap 23.jpgAs much as it hurts, killing Koro-Sensei is a necessary part of the story – because the story isn’t about Koro-Sensei. The story is about the students of the 3-E and their rise from the bottom of the barrel to the very top. Should Koro-Sensei continue to live, he’d act as a crutch for all the students, and from a writing standpoint, the students would never truly move on.

Whether it was right or wrong to kill Koro-Sensei is completely up for debate. It depends on where one stands regarding their moral viewpoints – there are bound to be differences. When it comes to questions about ethics, there is never a right or wrong answer. Only people with different ideas.screencap 24.jpg

This has been An Idiot’s Guide to Team Nagisa vs Team Karma – Would it be Right to Kill Koro-Sensei – but hey, don’t take my word for it. I’m just some idiot.