The Earth is threatened by a powerful creature who destroyed 70% of the Moon with its power, rendering into the shape of a crescent moon forever. The creature claims that within a year, Earth will also be destroyed by him, but he offers mankind a chance to avert this fate. In class 3-E at Kunugigaoka Junior High School, he starts working as a homeroom teacher where he teaches his students not only regular subjects, but the ways of assassination. The Japanese government promises a reward of ¥10 billion (i.e. 100 million USD) to whoever among the students succeeds to kill their teacher, whom they have named "Korosensei" . However, this has proven to be an almost impossible task, as he has several inhuman abilities at his disposal, including the capacity of moving at Mach 20.
"Assassination Classroom" is like its subject: not without its flaws, but hard not to love. A fresh take on the tiresome 'unconventional teacher that changes the lives of his students' genre, livened up by the students trying to kill their teacher.
The set-up is great: Class 3E, the losers of a prestigious high-school, are assigned a new teacher by the secret service, namely a betentacled monster that has announced he will destroy the earth in one year, and has requested to teach 3E in the meantime. If the students succeed in killing their teacher before the year is over, they will be granted a lifetime amount of money. And rightly so, for Koro-sensei (as the monster is dubbed) can reach a movement speed of Mach 20, outdoing the world's joint military resources. Mankind's last hope is the students learning Koro-sensei's weaknesses in time, although they may learn a lot more while doing so.
"Assassination Classroom"'s biggest asset is also its biggest strength: Koro-sensei. He is one of the most recognisable figures in anime; not only for his great design, but also his lovable personality: a caring and immaculate teacher, but also fussy, gluttonous and an incorrigible pervert.
The series' antagonists become as least as relatable. The demonic principal who created the school's authorial and ruthlessly hierarchic system and his son, the #1 student who has the others in his pocket - both of whom want to keep 3E subjugated - are intimidating in their own right, but their struggle amongst each other, the tyrannical parent who has never shown love, and the bitter son who wants to overthrow him, grants them a certain pathos. Near the end of the series their characters have nicely arced-out, to the point of becoming convincing human beings. Not in an overstated way, mind. The series does not ask us to love them, merely to understand them. The other antagonists are admittedly more one-dimensional, but then again: they are minor characters.
So far, the character building of "Assassination Classroom" is satisfying enough. The antagonists and deuteragonist (i.e. Koro-sensei) are very well developed. But there is one problem, a big one: the protagonists. Despite Koro-sensei's marketable image, the heart of the series lies with his students, and they are a mixed bag. The series revolves around their growth as students as well as human beings, but only marginally focusses on it. Of course it is difficult to keep up with twenty-eight students, and it would be harsh to demand all of them to have a breath-taking arc, but near the end of the first season, half of them is not even characterized. Where attention is given, it is done well: Nagisa, Karma and Kaede (all provided with a unique hair colour for convenience's sake) have more to them than shows and become endearing, but to the rest of the students fairly little happens, besides the establishment of one character trait: 'the one guy who is a pervert,' 'the one guy who wears glasses,' 'the one guy with the mushroom hair.'
Fortunately, the series has a saving grace: It is funny - really funny.
Humour is always a bit of a risk in anime. Take the first half of "Fullmetal Alchemist: Brotherhood," where throwaway jokes often undermine the drama. Not so in "Assassination Classroom," which manages to be touching as well as funny in a consistent way. At times it is even surprising how well the situations are handled. Two students pirating a rocket to rob the International Space Station (near the end of the second season) should have been the series jumping the shark, but the set-up and presentation are so clear and appropriate, that it all remains convincing.
Even if "Assassination Classroom" does not have a whole lot of substance, and its ultimate goal - to show the development of Koro-sensei's students - is not wholly reached, its heart certainly is in the right place. The characters are lovable, the writing is funny, and the storytelling is adept enough to pull the whole act off. Indeed, the series is like Koro-sensei: The more time you spend together, the more undesirable departing becomes.