Itou is learning how to be "normal" from her classmate Takahashi, who, despite being a monster in disguise, is a social butterfly. But suddenly, the very teacher Takahashi killed returns as a monster. This new "Niehara-sensei" has a terrifying agenda: to eradicate and replace the normies of the world. As Itou grapples with Takahashi's true nature--and her unwillingness to let Itou go--will she manage to stop Nie-sen before it's too late?