Season 1 - Episode Guide

The story of the original manga begins after 70% of the moon was suddenly vaporized in an explosion. The super lifeform responsible for this catastrophe is a strange tentacled creature that can slink around at supersonic Mach 20 speeds. It has a 10 billion yen (US$100 million) price on its head, but for some reason, this creature ends up teaching a middle school class at the beginning of the school year. The students have until graduation to assassinate the teacher, or it will destroy Earth as well. 

Koro-sensei reminisces about his first meeting with Karasuma, where they first butted heads and fought against each other, ultimately coming to respect one another. However, Karasuma eventually points out their actual meeting wasn't nearly as eventful.

A creature who blasted the moon into a crescent shows up at Kunugigaoka Junior High School and gives the students a year to assassinate him.

The reasoning behind the E Class's segregation is revealed. Nagisa tracks Koro Senei's weak points in the hopes of using them to take him down.

The brilliant, belligerent Karma Akabane, Nagisa's former classmate, joins 3-E and immediately jumps into the assassination mission with both feet.

A new foreign-language teacher comes to 3-E with some major ulterior motives.

Before the torturous school assembly begins, Okuda attempts to poison Kpro Sensei in an unexpected way. With unexpected results.

Koro Sensei gives his aspiring assassins an ultimatum as they battle a grueling test and disdain from the rest of the school.

The students go on a school trip to Kyoto where they must still keep assassination on their mind.

Kayano and Kanzaki are kidnapped by students from a rival school. The school is busy preparing for their long-awaited trip to Kyoto when it occurs.

A new student joins the E Class with a single minded focus on assassination that drives her fellow classmates to distraction.

Professor Jelavich is forced to prove her assassin skills when her mentor pays a visit to the school. Koro Senei takes Nagisa and Karma on a trip they will never forget.

A new assassin student with a goal to kill korosensei joins Class E.

The E Class boys must play the Baseball Club in an exhibition game meant to humiliate them.

Mr. Takaoka upsets others with his unconventional training methods when he comes to help Mr. Karasuma; Nagisa shows a hidden talent.

Koro Sensei exposes a major weakness while Terasaka interrupts a fun summer day with an assassination attempt that goes just a bit too far.

Final time arrives and Koro Sensei gives his class a new goal. He offers the class a tempting reward and the E Class makes a deal with the A Class's top tier Big Five.

The results are in after two days of exams. Both the ace A Class and the end E Class has to come to terms with the outcome as well as Koro Sensei.

The E Class trains intensely with a professional killer in order to prepare for their island assassination. Once they arrive at the island they must make sure everything falls in place.

The summer training assassination attempt is followed by a unexpected crisis that affects almost half of the E Class students.

The E Class students have to put the lessons they have learned into practical use when the unexpected crisis forces them to deal with a hotel full of bad guys without Koro Sensei's help.

The group of students from E Class head upwards in the hotel facing more assassins as they go.

The students meet the shadowy figure orchestrating their fellow students sickness after facing one last assassin. The mastermind wants Koro Sensei in exchange for the virus remedy.

The students of E Class arrive to a showdown on the roof as Nagisa battles for his fellow classmates lives.