A group of professional hitmen has arrived town. Karma is challenged for a fight but decided to swallow his pride after listening to Korosensei's advice.
As graduation day is approaching, Korosensei decides to create a graduation album which contains a thousand of photos of their memories that have been shared throughout this year.
At the same time, the final assassination plan has been carried out by the government. Heavy weapons and chemicals have been blasted to trap Korosensei. All these were carried out before the actual day of the earth destruction. The students run to the school for their final mission but unfortunately, all students are detained by a group of soldiers known as "The Wolfpack".
The uninformed attack has caused a difficult situation for the principal, Asano, and Karasuma who works in the Defence Department. Karasuma is stuck with his position and finds it difficult to offer his assistance to the students that insist to save Korosensei.
Three days left before they fire the laser. They received an unexpected help for their escape. With the time limit is just three hours, they work together as a team for their final mission.
This volume ends with the last 90 minutes before the laser will be fired. Two uninvited guests have entered into the barrier zone.
More reviews can be found on Goodreads: Assassination Classroom, Vol. 19: School Attendance Time (Assassination Classroom #19).