Akagami Aogami

Translated as "Red Paper Blue Paper", Akagami Aogami haunts the restrooms asking to his victims if they want red paper or blue paper. Both options are terrible ways of death, with "red" meaning the victim getting his blood drained out and "blue" meaning suffocation until the victim becomes blue due to asphyxiation. Answering with another color doesn't stop him either, as Hajime does so (in this case he answered "yellow paper") and is almost dragged to the underworld. Satsuki seals Akagami Aogami through a jar filled with water and marked with the symbol of a Torii. He appears in the 2nd episode and re-appears in the 20th episode.

(Source: Wikipedia)