9. The Death Of Koro Sensei - Assassination Classroom
With a title like Assassination Classroom, the story was never going to be one filled with loads of warm fuzzies. Even though viewers follow the attempts on the life of the aptly named Koro Sensei (a play on the Japanese word for “unkillable”) there is never a time where the oddly lovable, tentacled goof is in any real danger.
His relationship with his students and his aptitude as an educator harbor nothing but feel-goods toward the would-be destroyer of Earth. This alone is what makes his death so utterly heart-wrenching. As the series is based on the premise that, at some point, Koro Sensei is going to have to die, it’s not exactly that the death is unexpected, it's just that it is so undesirable.
After learning about Koro’s past and watching the care and attention he gives to each student in class E-3, knowing he has to die is the worst possible feeling—one encapsulated by the way all of the students break down in tears as Koro Sensei fades into the night.