Plus Minus Zero

What caused the massive earthquake is a mystery. Could it have been the time machine Gyungbae built? Was it the construction going on outside the school? Or was it something darker? Something that now lurks the hallways of the buried school, preying upon those who lingered? Whatever it is, the students and teachers trapped within the darkened halls of the school have more pressing issues to think about, like finding more food, whether they'll ever be rescued, and who stole Eunhui's body...