Corrupted School

The Corrupted School is very much like the school, with one major difference that Sabitsuki is being chased by the Kaibutsu. Most of the rooms here are blocked off by desks and it is an almost straight pathway to the basement.

Directons

The only way to reach the corrupted school is through a secret passageway randomly found in the Red Eye world 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 equipped 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.

As soon as you enter the actual school premises (room after the lobby) any effects you were using 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 Smile will kill Sabitsuki.

Rust Version

As of Version 0.15, you can go to the Corrupted School as Rust, simply by going to the Red Eye World as normal and finding the door. However, instead of three Kaibutsu, three Red Demons will chase you.

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.

Trivia
 * 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 and then she'll get up. This may be a glitch.
 * Like the Hospital areas, this event is similar to the school area.

Theories
 * Smile killing Sabitsuki 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.