"Assassination Classroom" is a Japanese manga series written and illustrated by Yūsei Matsui. It was adapted into several media formats, including an anime series, novels, and live-action films. The 2015 live-action film "Assassination Classroom" is based on the manga and anime series.
The story revolves around a class of students at Kunugigaoka Junior High School, Class 3-E, who are tasked with assassinating their alien teacher, Koro-sensei, before he destroys Earth. Koro-sensei is a powerful creature that has destroyed 70% of the moon and threatens to do the same to Earth within a year. However, he offers mankind a chance to avoid this fate: he becomes the homeroom teacher of Class 3-E, and the students are given the opportunity to assassinate him. To make things even more challenging, Koro-sensei is incredibly fast, immune to conventional weapons, and has several other abilities, making him nearly impossible to kill.
The students, who are usually considered misfits and academically weak, undergo rigorous training under the guidance of their government-assigned handler, Karasuma, and the professional assassin, Irina Jelavić. They use various creative methods and gadgets to try to assassinate Koro-sensei while dealing with their daily school lives.
As the story progresses, the students develop a complex relationship with Koro-sensei. Despite their initial fear and animosity, they come to respect and care for him as a teacher. The series explores themes of friendship, loyalty, and the value of education. While the primary goal of the students is to assassinate Koro-sensei, they also learn important life lessons from him, making their journey both humorous and heartwarming.
Please note that this is a general overview of the premise, and specific details may vary in the movie adaptation.