Spoiler warning: Read at your own risk. Premise Contrary to how it might seem Assassination Classroom isnt a shonen about kiling a tentacle monster anywhere except for the surface level. It is important to take a step away from the plots minutiae and actually consider it as a whole. At the end of the day what is Assassination Classroom about? AssClass is a story of regret. The main players in the plot in Assassination Classroom all regret. They either regret their strength or they regret their weakness and this idea of regret is used to set up a parallel between teaching and assassination. Pay attention to how different characters assassinate and teach for the same reason that Ill point out in the rest of this review. Teaching because of Regret Teaching and assasination. Author Yusei Matsui presents these two seemingly disparate professions as one and the same. So we must ask ourselves who are our teachers? KoroSensei and Principal Asano are our teachers and they are presented throughout the whole plot as rivals to each other. They differ in teaching philosophy methods morals and even genetic makeup but they both teach. Why? Well we can look to Chapter 125 for the answer to this. Two monsters became teachers at the same school. One because he regretted his strength. One because he regretted his weakness. Something interesting to note is that in other translations of AssClass this line is actually translated as One to atone for his strength and one to atone for his weakness. Principal Asano sees his weakness after his pupil dies as inexcusable and uses it as a reason to exert his forceful influence onto Kuunugigaoka resulting in the social structure we see in AssClass. KoroSensei on the other hand regrets his monstrous strength that results in the loss of his loved one. He realizes that hes done nothing but abuse his power and decides to assume a weak form that can protect his loved ones instead of a strong form that cant. Killing because of Regret Another major player in AssClass is Yanagisawa. Yanagisawas experimentation is what results in the birth of KoroSensei to begin with. What is his role? His parallel? What are his regrets? What is he atoning for? Well thats the thing. He doesnt. He doesnt atone for his actions regardless of how horrible they may be. Yanagisawa has regrets about his weaknesses but he doesnt atone for his mistakes. Yanagisawa is actually the contrast to Nagisa Shiota. Yanagisawa is a privileged man who knows all of the luxuries life can afford. He doesnt have to deal with hardship until his failure with the moon and almost fatal encounter with KoroSensei which results in him turning into the monster that we see at the end of the plot. Nagisa on the other hand is not so lucky. His grades are subpar his identity is a mess his family life is fractured and he has precious little to be proud of. When he discovers his talent for killing instead of getting a swelled head or flaunting it as a more boastful individual might Nagisa immediately goes to his beloved teacher and asks him for advice. This inherent considerateness is what separates Nagisa from Yanagisawa. If Yanagisawa discovered such a talent he would never bother going to anyone and talking them about it as he already sees himself above others. This establishes another parallel in our plot: Motives for killing. Nagisa targets KoroSensei because he regrets his newly discovered strength he wants to put his talent to a good use first to determine whether he should abandon it afterwards or not. Yanagisawa targets KoroSensei because he regrets his weaknesses to make himself forget that he is not perfect. Do you see where Im going with this? AssClass is full of these kinds of parallels that are there if you just pay attention. To Build or to Destroy What then comes as a result of this regret? What do our characters do with it? KoroSenseis regret causes him to fill in as 3Es homeroom teacher for a year. During this year he does his best to build. He builds trust he builds relationships with his students he builds his students skills whether they be academically physically socially or emotionally. He does anything and everything to protect the lives and happiness of his students. His presence is felt in his students lives even after his death as is seen with his effort in helping Nagisas family reconcile. Principal Asanos regret causes him to make power plays in escalatingly dire ways. He plays dirty and he does it often. He erodes his schools morals he discriminates against 3E with gusto and this all eventually comes crashing down upon him as the student body loses trust in him and he eventually is forced to resign. He might have seen his ideology as strong but in reality he was still just as weak as always. Nagisas regret leads him to work as hard as he can to prove himself worthy of his strength. He constantly does his best whether by studying for a test or by beating the ever living shit out of Karma to try to save KoroSensei. Hes built a meaningful relationship through the year with all of 3E and his goal of killing KoroSensei comes to fruition in the most tragic way possible. His experiences with KoroSensei have built an entire world of experiences and a plethora of relationships but it came at the cost of KoroSensei. Yanagisawas regret leads him to constant suicidal bids at KoroSenseis life. These bids go from Itona to Kaede to the Reaper to even his own body as he uses the tentacles to artifically give him power. His goal of killing KoroSensei die however never comes to fruition as he gets launched out of the Thunderdome and it ends up being the students of 3E who kill KoroSensei. His quest for strength results in his own destruction. What does this even mean? Matsui is trying to tell us that building is the only way to truly be strong. If you try to burn all your bridges in order to seek power it will absolutely come crashing down upon you and it will not end well. Nagisa takes this to heart and becomes a teacher himself taking on KoroSenseis role in the future. Basically what Im saying is AssClass tells you that Those who can kill teach.