Class 3-E at Kunugigaoka Middle School returns from their summer vacation to encounter an insurmountable challenge. The looming prospect of global annihilation forces the students to devise increasingly intricate and innovative strategies to eliminate their teacher, the cunning yet helpful Koro-sensei. Their quest to vanquish Koro-sensei is not their sole focus, as Gakuhou Asano, the cruel and pitiless principal of the prestigious academy, endeavors to hinder the success of Class 3-E by indoctrinating his other hardworking students into ruthless competitive study machines. The ensuing hostility sparks internal conflict as traitors and killers vie for the bounty on Koro-sensei's head. A prominent Class 3-E assassin, Nagisa Shiota, finds himself embroiled in the turmoil. Amidst his academic pursuits and the fight to save the world, domestic conflicts threaten his position in Class 3-E. Together with his loyal classmates, Nagisa must confront these challenges head-on.