You were in class 3 - E, which was the worst class in the school, You and your other classmates were sent to an abandoned school which was completely destroyed. The building is located one kilometer away from the main building up on a nearby mountain. The trail between the Main Campus and Class E, in addition to the uphill trek, is riddled with a number of natural obstacles, such as snakes, bees, and rivers.

You were sitting in the classroom which had 29 seats, a teacher's desk, a small stand for the teacher, a chalkboard, finally broken glass on the floor since it was destroyed of course and some of the windows were broken. Just then, a 3m tall alien-like of a yellow octopus walks in.

" Hello class! I will be your new teacher! I am Koro Sensei, or you guys could call me Mr. Koro!! You will all have to assassinate me before graduation! any questions?~ "

You and your other classmates were shocked by what he said, the weirdest thing was that he was speaking in an excited and happily tone.... why is that....?