"I don't understand,why do I have to go to 3-E?" "There is no reason." Hakuya Hiyori is a student who always gets perfect grades which is better than Asano Gakushu.Although nobody knows this except the principal,the teachers and herself.The reason for this is because she hates attention and likes to hide her presence from everyone.Despite her perfect grades she is suddenly transferred to 3-E,for an unknown reason and now she learns that she has to kill Koro-sensei until her graduation.