In just one year, the students of Class 3-E in Kunugigaoka Junior High underwent life-altering changes under the guidance of their unconventional mentor, Koro-sensei. Nagisa Shiota and Karma Akabane, two alumni of the class, hold this period in high regard as it marked pivotal turning points in their lives. As they return to their former classroom, they are transported back to the defining moments that shaped their transformation into proficient "assassins" and better equipped them to handle the realities of life. This development was fueled by their unique teacher's influence, Koro-sensei, whose initial plan for eldritch destruction was overtaken by the extraordinary and unorthodox "Assassination Classroom."