Ghoul School

You play as a kid who has to fight monsters in school (I wonder what he does there at night), using a ruler as a weapon. The monsters have to be hunted down by class, and there are a lot of classes. Each floor is crawling with monsters. You can hide in cubicles (it's strange that there's nothing in the cubicles, it must be the holidays). The music only changes when you enter the classrooms. There are more weapons and defences, but you still have to find them.