Class 3-E

Earth is left in disarray when all of a sudden, 70% of the Moon is obliterated, leaving it permanently in the shape of a crescent. Not long after, a yellow tentacled creature appears to claim responsibility for the phenomenon. He soon proves to be unable to be killed by the world governments due to his arsenal of superpowers including accelerated regeneration, visual cloning, near-impenetrable skin, and the ability to move and fly at Mach 20. The creature claims that within a year, he will destroy the planet next. However, he offers mankind a chance to avert this fate. Per the resulting agreement, the creature becomes a teacher at Kunugigaoka Junior High School, his students being members of Class 3–E, a class that is intentionally disadvantaged academically due to low grades, inability to meet the school's strict rules and policies, and other forms of cruel and unusual punishment. Each of the students are granted the chance to kill the creature, whom they dub "Koro-sensei", before his imposed deadline of the end of the school year, and are granted specialized weapons developed by the government that can kill him; furthermore, Koro-sensei is forbidden from harming the students in any capacity. In addition to teaching them regular subjects, Koro-sensei also teaches them the ways of assassination so that they can kill him in the future. The Japanese government promises a reward of ¥10 billion to whoever among the students succeeds in killing Koro-sensei. However, this proves to be a virtually impossible task not only due to his superpowers and death anxiety, but because he is also the best teacher they could ask for, helping them to improve their grades, individual skills, and prospects for the future. Because it is secluded away from the main building, the students and teachers are able to carry out their assassination attempts without the people from the main school knowing or noticing.