What is it?
The 2015 Japanese anime TV show Assassination Classroom (Season 1).
My brother GC saw this anime before it even was shown on Toonami, he showed me a scene from the first episode, but I did not watch this show until it aired on Toonami recently.
This season was not as good as I had expected, the tone was surprisingly light & positive most of the time, which I was not expecting, and which worked better than you would expect for a show called Assassination Classroom.
While this show did not connect with me that much, I do like how the characters learned to work together & grow, and I was impressed with how well the teacher student concept worked.