Gakkou no Kaidan

Synopsis

The next day in school, the flushes of the new school building's restrooms start malfunctioning, prompting the teachers to instruct the children to use the old school's restrooms. There, a monster, Akagami Aogami, frightens people by asking them if they want red paper or blue paper. Both options represent different terrible ways of death, "red" meaning the victim getting his blood drained out and "blue" meaning suffocation until the victim becomes blue due to asphyxiation. Hajime tries to trick the demon by answering "yellow" and opens a vortex to the spirit world instead. Satsuki seals Akagami Aogami using a jar filled with water and marked with the symbol of a Torii, rescuing Hajime in the process.

(Source: Wikipedia)