The corrupted school is very much like the school with one major difference: you're being chased. As soon as you enter the actual school premises (room after the lobby) any effects you were wearing will be disabled and you will be unable to use any of your effects. Kaibutsu with steel pipes will chase you as you head down to the basement where an old friend will be there to greet you.
Most of the rooms here are blocked off by desks and it's an almost straight pathway to the basement. It's important to always keep moving.
The only way to reach the corrupted school is through a secret passageway randomly found in the Red Eye World (see picture below) which will lead you to a hallway lined with smiling mouths leading to three Kaibutsu who will begin to chase you back down the hallway. If you do not have the ghost effect equiped and in use the Kaibutsu will catch you. You will see a path to the left that wasn't there when you first came in and that leads you to the corrupted school.
When going through the actual school, instead of the Sabitsuki-lookalike Kaibutsu chasing you, large Red Demons will chase you. Any Kaibutsu that appears will scream and become one of the bigger Red Demons.
Eventually at the basement Rust will become a Kaibutsu and will kill Smile with her pipe if you talk to him.
- This is the only event when the Sabitsuki-lookalike Kaibutsu appear, and they are the only Kaibutsu to appear in the event. The same is true for the giant Red Demons.
- If you try to go back at the gates of the school, you will here static as the screen goes black. You will reappear at the entrance of the mouth you went in. Sabitsuki will be sitting then she'll get up. The sitting may be a glitch.
- When you get to the bottom of the corrupted school Smile will kill you. This could be interpreted as an emotional killing that when Smile took her down to the basement and told her to leave him and his sister alone it was an emotional and social death to her as she's now lost her only friend.
- Following the theory above, this means that Rust's version is essentially Sabitsuki getting revenge on Smile for what he did to her.