Episode Title:Past Time.Episode Description:Over the course of a year, The Reaper's body continued to be altered by the experiment while his relationship with Aguri continued to grow stronger. Meanwhile, an experiment testing the effects of the tentacle formula on a rat proved disastrous, causing the explosion that destroyed seventy percent of the moon. Learning that the same thing may happen to him in a year's time, The Reaper unleashed his new powers in an attempt to escape from Yanagisawa's facility killing several guards and making Yanagisawa loose his left eye. As Aguri tried to keep him from leaving, she was fatally wounded by one of the facility's traps, asking him to watch over Class 3-E in her place. Devastated by Aguri's death, The Reaper wished to be weak and flawed, and his tentacles transformed him into the kindhearted teacher Koro-sensei. Back in the present, as the students are troubled over the thought of having to assassinate the teacher they had grown to admire, Nagisa states his desire to find a way to save Koro-sensei's life.