began around one year before the Killing School Life that befell the students of Class 78th and was triggered by The Tragedy of Hope's Peak Academy.
The Tragedy has been described by various people as being an extraordinary form of social unrest, which quickly escalated into uncontrolled, meaningless chaos, violence, and death. This incident was caused by Junko Enoshima and the Ultimate Despair.
It was ultimately terminated thanks to the combined efforts of Ryota Mitarai's brief broadcast of the Hope Video and the Future Foundation's involvement in helping rebuild the world.