Assassination Classroom

After destroying the moon, an inhuman nigh unkillable creature has decided to destroy the earth in less than a year. For some reason, he has decided to become a High School teacher and under no circumstances will harm his students. His students now have to kill their teacher before he destroys the planet. This may be more difficult than expected, however, as not only Koro-sensei (the name they decided to call the creature) night unkillable, he also is the best teacher they have ever had.

Assassination Classroom is a manga series written and illustrated by Yūsei Matsui. It originally ran in Shonen Jump from July 2012 to March 2016, compiled in 21 volumes, and is licensed in North America by Viz Media. It has had two anime adaptations, a single OVA episode in 2013, followed by a TV series in 2015. It also has two live-action adaptations, released in 2015 and 2016.


 * Detonation Moon: And earth is next if Koro-sensei isn't killed soon enough.
 * Kryptonite Is Everywhere: To be fair, the threat that is Koro-sensei is a closely guarded secret and anyone other than world leaders let in on that secret is more likely than not supposed to kill him and has been supplied special weapons suitable solely for the task of killing him (in fact often these weapons are unsuitable for killing humans).
 * Nigh Invulnerability: Koro-sensei.
 * No Endor Holocaust: Considering that 'only' blowing up the Moon to the extent that it was rendered a permanent crescent would be enough to initiate at least a Class 3 Apocalypse in Real Life, the inhabitants of the Assassination Classroom universe sure are lucky to be anime characters.