it's basically just students trapped in a high school by a robotic black and white bear named Monokuma
and essentially, he forces them into a killing game where if three or more people find a body, he will announce it and an investigation will start and the students will have to investigate to find the culprit and do a trial.
During the trial they will have to use evidence to weed out the culprit, before going through a majority vote on who they think it is.
If they vote correctly, the culprit will get executed and they will continue their "school life"
but if they choose wrong, everyone else besides the culprit will get executed and the culprit will be able to "graduate" AKA being set free