Karma is bored,so he decides to text strangers on the internet that are not japanese,like this he 'met' Y/n, a(what ever city,state you want) girl. After a year of texting, she got the opportunity to go live in Japan and she signed for the same school as Karma.in that exact year,a powerful, tentacled alien creature destroys 70% of the moon, leaving it permanently in a crescent shape. He threatens to do the exact same thing to Earth in one year. However, he offers humanity a strange compromise: he will delay the destruction if he is allowed to teach Class 3-E at the prestigious Kunugigaoka Junior High School. The government accepts, and the students of Class 3-E are given a secret mission by the Ministry of Defense: assassinate their new teacher before the school year ends. If they succeed, they win a reward of 10 billion yen.Koro-sensei: The alien teacher (whose name is a pun meaning "unkillable teacher"). Despite his threat to destroy the world, he turns out to be the best, most caring teacher the students have ever had. He can move at Mach 20, making him nearly impossible to hit, but he genuinely wants his students to succeed both in their studies and in their assassination attempts.Class 3-E is known as the "End Class." It’s where the school dumps its lowest-performing or misbehaving students to act as a negative example for the rest of the student body. They are isolated in a rundown building on a mountain. Koro-sensei changes everything for them. Instead of treating them like failures, he uses his superhuman abilities to give them personalized education, boost their self-esteem, and teach them valuable life lessons through the art of "assassination" (which becomes a metaphor for overcoming their personal obstacles).