I hope that teacher will arrive soon.
The School (学校, Gakkō) is an area accessible from many locations, including a Mantis student in the Blue Forest, and the Apartments through a similar route that you would take to get the Spring effect.
The main part of this area is a long white-walled corridor with multiple doorways leading to different classrooms. As you progress downwards, the desks and rooms become more cluttered and contain NPCs such as a black cat and a moving eyeball.
There is a white-haired teacher patrolling the corridor who will get mad at you if you ride your bike, and chase after you. If he catches you, you will be sent to what appears to be some kind of staff room where you will be in "detention", meaning that if you try to walk away, the teacher will jump up and down and force you back to your place. Like with the Chasers, your only method of escape will be to use the Eyeball Bomb effect. If you use the Glasses Effect on the teacher, you will see that he is a ghost. If you chainsaw him while you are in detention, he will disappear like other NPCs, then become a ghost and follow you around the "staff room". Running into him will cause his sprite to change briefly before Urotsuki wakes up.
By interacting with the doors at the other end of the classrooms, you can go outside to a balcony; if you come here from Cloud Tops, this balcony is where you will land. Here you will find a small boy clapping erasers. Using the School Boy effect on him will make him move out of your way (you cannot chainsaw him). When you go into the last classroom (which is locked from the corridor side), you will see a girl looking out the window at the boy. If you are using the School Boy effect when you walk in, the girl will be looking lovingly in your direction. If you use the Glasses Effect, the boy and the girl will become transparent.
A small hole in one of the classrooms walls will take you to a small pipe that you have to crouch through. Upon reaching the end, it will take you to the underwater area of the Dream Beach
Interacting with the black cat in one of the classrooms will lead to an area with a large cat in the background and two cat girls (one black, one white) that will take you back to the classroom. Interacting with the large cat will make it purr. Urotsuki is also able to sit on its arm.