One day, government officials arrived at the classroom of the failing students at the famous Kunugigaoka Junior High.
They arrived escorted by an arrogant tentacled creature. It had reason to be arrogant, as it had just reduced 70% of the Moon to dust. Since its next act is the annihilation of Earth, it came to announce its plan to humanity.
The reaction of humanity was the healthiest possible: attempting to eliminate the creature before it could carry out its plan... The only drawback is that it moves at hypersonic speed.
No elite army or seasoned sniper managed to hit such a fast target. Running out of solutions, the planet's governments decided to entrust the heavy task of eliminating this threat to Class 3-E.
Indeed, for a still mysterious reason, the creature wished to become the teacher of this particular class. The initially bewildered students agreed to play along upon the announcement of a 100 billion yen reward. Class 3-E remains composed of makeshift killers. Since then, the students have had to plot daily to find a way to eliminate their peculiar homeroom teacher before the end of the school year.
This strange octopus-like creature has become their target to take down! They must now be ingenious to kill a teacher who moves at Mach 20 and regenerates in seconds. The worst part is that he is quite a good teacher! He knows how to maintain order in his class: "Assassination attempts must not disrupt classes."
But be careful, the students of Class 3-E are not the only ones! A highly trained Defense Ministry agent disguised as a gym teacher and hitmen acting as substitute teachers are there to coach them and attempt to assassinate Korosensei themselves. A turbulent school year is in store for this killing class!